Hi Ben,
There is another useful measure for counting the issues having transitions in a field:
[Measures].[Transitions to issues count] for counting the distint issues having the transitions.
This formula should also use the specific transitions field to count only on the chantes in the Priority:
Aggregate(
{[Priority].[Critical - Do ASAP],[Priority].[Blocker - Do NOW]},
([Measures].[Transitions to issues count],
[Transition Field].[Priority])
)
Kindly,
Janis, eazyBI support