Count function based on region ignores region visual filter

Hello everyone,

I am quite experienced with Power BI, but there's something that I am not understanding.

I have a banal function:

"Count_Customer_Japan = CALCULATE(COUNT(Customer[Customer]); Cities[Region] = "Japan")".

I have created a visual object that shows this measure and a visual filter based on the region.

Whatever region I choose in the visual object filter, the measure shows the same amount of persons.

Shouldn't the filter filter the measure and shows an amount equal to zero when I select a region different from Japan?

Here it is the screen:

I'd upload the .pbix, but I never remember how to do it.

Many thanks!