Dataflow gen2

Hi,Marian1981 .I am glad to help you.

Have you tried turning this off to see if that alleviates the problem.

According to the documentation, when the auto-hosting setting is turned on, Gen2 Data Streams automatically manages the mappings, including automatically updating or deleting the target table when the source table changes or is deleted. This may cause the system to automatically manage mappings between tables when you save this gen2 dataflow, resulting in some information as well as created MEASURES being deleted.
The Auto Managed Settings feature is turned on by default, you can try turning this button off to see if it alleviates the problem.

URL:
Dataflow Gen2 data destinations and managed settings - Microsoft Fabric | Microsoft Learn

Please also try other possible suggestions, such as artificially removing the deletion action steps added by the system. If you can provide more detailed information (screenshots without sensitive data), it will help to solve the problem.

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Carson Jian,
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