Slicer does not filter visual

[NenadV]

I have data model with three tables:

and here is data from these tables:

and now I want to create report with one slicer with nameA values, and one table, with nameB column and number of rows in table C, so I created measure: Measure = COUNTROWS(Table C) + 0 (I added +0 at the end because I want to show 0 instead of BLANK when there are no rows in Table C that match selection). Something like this:

and here is the problem, when I select some value from slicer, "a" for example, this is what I get:

but that is not what I expected, I just want to see: 

a	0
aa	1
aaa	2

So  slicer is filtering values from table C and counting them but it does not filter nameB column values.

I tried removing +0 from the measure and now it is returning just

a
aa	1
aaa	2

as expected.

Can someone please explain me what is happening here, and how I can get wanted result.

[BA_Pete]

Kudo'd OP for a really well-presented and clear request. An example of how help requests should look!

Pete

[AllisonKennedy · Accepted solution]

You can try doing 

Measure = SUMX(TableB, 0 + COUNTROWS(C))

Adding +0 to a measure can act as a cross join or clear filters when multiple table relationships are involved. 

[NenadV]

Thank you very much @AllisonKennedy , you helped me a lot. Your solution is working well.