Power BI Service & On Premises Data Gateway

Hi,

I'm pulling my data from a on-prem SQL Server.
I used one of our "standard" Power BI pbix files and enchanced it with customer specific tables

Once I publish the report to a workspace and check the settings of the dataset, to change it to a datasource i've setup in the gateway I see following message:

I don't understand why the Power BI Service is saying this...

I have checked the customer specific pbix file and I only have one datasource which is the on-prem SQL server.

I have tried following things:

1. I made a copy of the pbix file and removed all tables and kept my parameters => kept giving me the same message

2. I created a blank pbix file, read 1 table from the same SQL server => I could setup the datagateway correctly

3. I made a copy of one of our standard pbix files (without any customer specific tables) and published this one =>I could setup the datagateway correctly.

4. I tried working with the IP address of the server => kept giving me the same message

5. I tried installing an older version of the gateway => still same error

I'm running the latest version of Power BI Desktop and On-Premises Data Gateway (June 2020).

Anyone else ever experienced this behaviour?

I'm out of ideas and I don't really want to start from scratch since this was a few days work to get the data correctly.

Regards,

Kevin