Filter showing unexpected blank value

Hi guys,

i have a date filter which shows a blank value which shouldnt be there:

This is the setup:

Revenue table as basis and date table connected with it. No other relations. The date table is created with: 

Date = CALENDAR(MIN('PC Calculation'[dBezahlt]); MAX('PC Calculation'[dBezahlt]))

 

So the date table naturally encompasses all the dates that are prevalent in the revenue table.

 

To double check that all dates from the revenue table are also in the date table i created a custom column in the revenue table. In that column i look up the dates from the date table to check if any blank values are being produced. But there are none: 

 

 

Any ideas why the filter still shows a blank value? 

 

Thx!