SUMX producing wrong result when filtered in both row context and filter context

Hello jaap_olsthoorn, AlbertoFerrari, Anonymous,

I was very curious about this issue when I read it this morning and now I could have a look. Here's what I found:

I would like to begin with Alberto's own words:

"The golden rule of data modeling is always the same: always use star schemas."

https://www.sqlbi.com/articles/understanding-dax-auto-exist/ 

I believe that these words should be written on the first report page in every new Power BI file created.

Then following these words, if you create an actual star schema instead of flat table, this issue is non-existent.

data model (DimOwner is created as distinct in Power Query from Test Table):

and above data model produces this result when only adding new slicer from DimOwner

I understand that jaap_olsthoorn  you're curious why is this happening, but for everyone finding this thread, in my opinion the best workaround is to just follow what Alberto and Marco are teaching us...

Always use star schemas

Wiliam Juricek

https://powerbipro.eu/en/index-en