Starting with the release of Strategy ONE (March 2024), dossiers are also known as dashboards.
SYMPTOM
Using Data Combination setting as "Min relation..." a dossier with derived attributes based on multiple attributes fails with "Unspecified error".
STEPS TO REPRODUCE:
1. This example uses Strategy Tutorial to demonstrate the problem and the fix.
2. Create a standard report like the following:

3. Create a dossier using the above report and create following derived metrics:
Case String01 = Case((Region@DESC="Central"), "C", (Region@DESC="Souththeast"), "S", (Region@DESC>"N"), "N", 0)

Case String02 = Case((Region@DESC>"S"), Cost, (Region@DESC>"N"), [Day@ID], [Region@DESC])

Case String03= Case((Day@ID>39100), '1/20/2007', (Day@ID>39150), 1000000, (Day@ID>39180), "Day2009", "Default")

4. Create a visualization like the following:

5. Go to Query Details and following CSI is observed:
********* Visualization Summary Start ********** Time Spent: 0.077 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM Note: The total 'Time Spent' above may be greater than the summation of the individual step execution times below.There are preparation tasks for each step that are not individually measured. ********* Visualization Summary End ********************** Individual Step Start ************ Number of Rows Returned: 21 Time Spent: 0.002 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Case String03]@[ID], [Day]@[DAY_DATE] from RELATION0-<Case String03, Day>to Ex7_tempcube0 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Region]@[REGION_ID], [Day]@[DAY_DATE], [Case String02]@[ID] from R031 Dataset for case functions R-D-PRCto Ex7_tempcube1 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Region]@[REGION_ID], [Day]@[DAY_DATE], [Case String02]@[ID]from Ex7_tempcube1 to RELATION5-<Region, Day, Case String02> ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.000 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM Drop Ex7_tempcube1 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Case String02]@[ID], [Region]@[REGION_ID], [Day]@[DAY_DATE] from RELATION5-<Region, Day, Case String02> to Ex7_tempcube2 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 7 Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Case String01]@[ID], [Region]@[REGION_ID] from RELATION3-<Case String01, Region> to Ex7_tempcube3 ************ Individual Step End ********** *********** Some SQL for some of the Runtime Datasets might be unavailable at this time. ********* ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.002 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Case String03]@[ID], [Case String02]@[ID], [Case String01]@[ID], [Region]@[REGION_ID], [Day]@[DAY_DATE] from Full Outer Join( Ex7_tempcube3, Full Outer Join( Ex7_tempcube0, Ex7_tempcube2 ) on Day ) on Region to RELATION6-<Case String03, Case String02, Case String01, Region, Day> ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.000 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM Drop Ex7_tempcube0 ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.000 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM Drop Ex7_tempcube3 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.003 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select * from Left Outer Join( R031 Dataset for case functions R-D-PRC, RELATION6-<Case String03, Case String02, Case String01, Region, Day> ) on Day, Region, Case String02 to Ex7_tempcube4 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.007 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM select [Day]@[DAY_DATE], [Region]@[REGION_ID], [Region]@[REGION_NAME], [Case String03]@[ID], [Case String02]@[ID], [Case String01]@[ID], [Revenue], [Profit], [Cost], [Average Revenue] from Ex7_tempcube4 ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:40:47 PM Query Execution End Time: 2/11/2019 6:40:47 PM Drop Ex7_tempcube4 ************ Individual Step End ************

Note that the visualization fails to execute.

Go to Query Details and following CSI is observed:
********* Visualization Summary Start ********** Time Spent: 0.045 sec(s) Query Execution Start Time: 2/11/2019 6:54:05 PM Query Execution End Time: 2/11/2019 6:54:05 PM Note: The total 'Time Spent' above may be greater than the summation of the individual step execution times below. There are preparation tasks for each step that are not individually measured. ********* Visualization Summary End *********** *********** Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.003 sec(s) Query Execution Start Time: 2/11/2019 6:54:05 PM Query Execution End Time: 2/11/2019 6:54:05 PM select [Day]@[DAY_DATE], [Region]@[REGION_ID], [Region]@[REGION_NAME], [Case String02]@[ID], [Revenue], [Profit], [Cost], [Average Revenue] from R031 Dataset for case functions R-D-PRC to Ex10_tempcube0 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 21 Time Spent: 0.001 sec(s) Query Execution Start Time: 2/11/2019 6:54:05 PM Query Execution End Time: 2/11/2019 6:54:05 PM select [Case String03]@[ID], [Day]@[DAY_DATE] from RELATION0-<Case String03, Day> to Ex10_tempcube1 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: Time Spent: Query Execution Start Time: 2/11/2019 6:54:05 PM Query Execution End Time: select [Case String03]@[ID], [Case String01]@[ID], [Region]@[REGION_ID], [Day]@[DAY_DATE] from Ex10_tempcube1 to RELATION7-<Case String03, Case String01, Region, Day> ************ Individual Step End ************

Go to Query Details and following CSI is observed:
********* Visualization Summary Start ********** Time Spent: 0.049 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM Note: The total 'Time Spent' above may be greater than the summation of the individual step execution times below.There are preparation tasks for each step that are not individually measured. ********* Visualization Summary End ********* ************* Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.003 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM select [Day]@[DAY_DATE], [Region]@[REGION_ID], [Region]@[REGION_NAME], [Case String02]@[ID], [Revenue], [Profit], [Cost], [Average Revenue] from R031 Dataset for case functions R-D-PRC to Ex10_tempcube0 ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.002 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM select * from Left Outer Join( Ex10_tempcube0, RELATION0-<Case String03, Day> ) on Day to Ex10_tempcube1 ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.000 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM Drop Ex10_tempcube0 ************ Individual Step End ************ ********* Some SQL for some of the Runtime Datasets might be unavailable at this time. ********* ************ Individual Step End ************ ************ Individual Step Start ************ Number of Rows Returned: 147 Time Spent: 0.006 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM select * from Left Outer Join( Ex10_tempcube1, RELATION3-<Case String01, Region> ) on Region ************ Individual Step End ************ ************ Individual Step Start ************ Time Spent: 0.000 sec(s) Query Execution Start Time: 2/11/2019 7:03:45 PM Query Execution End Time: 2/11/2019 7:03:45 PM Drop Ex10_tempcube1 ************ Individual Step End ************