Distinct Count calculated wrong

Hi,

I want to make a KPI counting the Participants in a survey. When I have the participants in a table it shows correctly, but once I transform these into a count or distinct count it shows incorrectly.

You can see below what I mean:

Don't summarize:

Distinct Count:

I want to make a card showing the KPI of 1 instead of 5 - because you can see there's only one participant when I 'Don't Summarize'.

I have tried all three posibilities in terms of joins from the two tables (Both, table1 filters table 2 and table 2 filters table 1).

I hope someone can help.

Thank you! 🙂