Hi @Gottfried
Only one source can be set in the search result source settings. This is also the situation you encounter. Either you can only choose the content in the online environment, or you can only choose on-premise.
It is a by-design behavior, and the use of custom query rules in hybrid search has certain restrictions.
What I can advise you is not to use a custom query rule. If you only want to display search results from on-premises, you can use the "isexternalcontent:1" property.
For example:
This returns only on-premises results.
Thank you for your understanding.
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