Cthulhu
Why Cthulhu? Because the mental gymnastics required to figure this out nearly drove me insane. And because the exact reason you would need this measure is probably beyond the comprehension of mere mo...
I may be a 3rd guy... Looks like I may be using this work.
I would have preferred a Power Query based solution, as the mix of PQ and using add column or measure is a bit too unpredictable for a beginner like me. I have lots of PQ in a complex table, along with using this, as an add column.
It worked! But devs are buffled as to how it is all works.
Amazing work - I've just signed up to say thank you!...