Filter issuev - Context transition

Hello, thanks for your answer amitchandak .

This does work indeed for the first and third example (in my original post) but it doesn't work when I use the page filters IsBeforeThisMonth and Year AND if my table includes the year dimension as well. Question is: why is example 2 not working but 1 (another scenario where I use the Year dimension in my table and only use the IsBeforeThisMonth filter as a page filter) and 3 are? What is different causing the measure not to work in example 2?
So focussing on example 2 and 3: everything works fine without Year dimension in my table and using both page filters (IsBeforeThisMonth and Year) but after adding the Year dimension in my table the measure calculates the average over the total Year taking abstraction of the YY-MM field.

This works (last example of my orignal post):

This doesn't (second example of my original post):

 Any idea? Many thanks!!