To identify testcases mapped to testexecution based on Test label

Thanks, @rajm, for additional information!
Xray test run-related measures like “Xray Test Runs” are grouped by Test Execution fields by default (see documentation: Xray Test Management).

However, you can create a calculated measures (in Measures section) to change the relation of the “Label” dimension and measure “Xray Test Runs”.

The expression might look like this:

Sum(
 --filter set of Tests
 Filter(
  Descendants([Xray Test].CurrentMember,[Xray Test].[Test]),
  --Test issue has selected Label
  DefaultContext((
   [Measures].[Xray Tests created],
   [Xray Test].CurrentHierarchyMember,
   [Label].CurrentHierarchyMember
  )) > 0 ),
 --sum up test runs ignoring Component assigned to Test Execution
 ([Measures].[Xray Test Runs],
 [Label].CurrentHierarchy.DefaultMember)
)

Here are few more topics on similar use cases how to analyse Xray test runs by Test fields, not Test Execution fields: