Power Query in Semantic Model Web Editor: privacy settings don't allow the combining of data from mu

When editing tables (queries) in an import mode semantic model in the service (web editor -> transform data), I often get this error message:

Underlying Error Privacy settings don't allow the combining of data from multiple sources in the same query. \n\r To refresh this dataflow you can either edit the queries or you can allow combining data from multiple sources in the Edit queries Options settings. 

There is no option to fix the issue. And obviously the error message is misplaced (this is not a dataflow and there is no Edit queries Options settings...)

I don't get the same error in Power BI Desktop when doing the exact same changes. I guess it's a bug in the web editor. And - even if wasn't a bug - there is also no option to change privacy settings in the web model Editor.

See:

https://www.reddit.com/r/MicrosoftFabric/s/elvbst95GY

This is a blocker for using the Web Editor for import mode semantic models.