Also, I have a Report level filter applied. I am using "is not blank", so nothing actually is being filtered out. The issue is also reproduced with any filter applied on Product Column.
Everything is OK until a filter on Category is applied.
As you can see measure [Sales All Sales Categories]fails to show values for all categories. But when I remove Report level filter on Products everything starts to work as expected.
I think that is because of SummarizeColumns function. Here are 2 DAX expressions that are returning different results: one is with SummarizeColumns, the other is the same, but written with Summarize/AddColumns.