KB46021: An Information Window set to position "Fixed" will change its position after scrolling down on the document in Express mode in MicroStrategy Web 9.3.1.

SYMPTOM:
In Strategy Web 9.3.1, the placement setting for an Information Window can be set to 'Fixed'. This will ensure that the position of the info window be locked in one location. In Express mode, when a user runs the document and opens the info window, it will display in its fixed location correctly. However, if the user then closes the info window, scrolls down, and triggers it again, the location of the info window will be changed to appear within the visible area of the screen and not in the previous location, that may have disappeared from the screen due to the scrolling, as shown below:
Before scrolling:

Notice how the info window appears covering the "Electronics" element.
 
After scrolling down:

Notice how the info window appears covering the "Music" element, instead of being fixed on top of the "Electronics" element.
 
The location is fixed correctly in Flash mode as shown below: 

 
Notice how the info window always displays covering the "Electronics" element.
 
STEPS TO REPRODUCE: 
Follow these steps to reproduce the issue in Strategy Tutorial Project:

• Create a report with the attribute Category, Subcategory and the Cost metric.
• Create a document from that report.
• Add a panel stack to the document.
• Add the report as a grid to the document and to the panel stack.
• Make the panel stack an information window with placement set to Fixed as shown below:
  

• Outside of the info window, make Category a selector that targets the panel stack. This will be the info window's trigger.
• The final document will be similar to the image below:
  

• Run the document in Express Mode in Web 9.3.1.
• Select a Category element to display the info window and notice it displays in the appropriate fixed location.
• Close the info window and scroll down on the screen and repeat step 11 to see the position of the info window changes as shown above.
• Repeat step 11 and 12 in Flash mode to see the position is fixed in both scenarios as shown above.

CAUSE:
This is a known issue in Strategy Web 9.3.1.
 
ACTION:
This issue has been addressed in Strategy 9.4.0. Upgrade to this version to take advantage of the fix.
 
WORKAROUND:
If possible, run the document in Flash mode instead to avoid this issue.