SYMPTOM:
After executing a report with a metric defined using element prompts the following error will generate:
Error(s) occurred while loading report: DSSSQLEngine: Schema loading error: Template (Local Template). -Template Unit Metrics-Template Metrics-Dimensional Metric (<metric name>). -Dimensional Metric-Unsupported object type in Metric

Steps to reproduce
1. Create an attribute element prompt (e.g. Year)
2. Create a metric using either definition: ApplySimple("Sum(#0)", ?Year) Or ApplySimple("Sum(#E0)", ?Year)

3. Add the metric to a simple report and execute.
CAUSE:
This is currently working as designed. Strategy does not currently support element prompts inside of metric definitions. There is an enhancement request to support this feature.
ACTION:
Contact Strategy Technical Support to find out the status of the enhancement.