Hi @Lorne Andersen ,
We'd recommend you check if the related M365 group get deleted by accident. Please navigate to Admin Center as admin > Teams & Groups > Active teams & groups to check if associated group still appear in the list.
If we delete the group from there, the error will prompt in our test.
We'd recommend you then navigate to the deleted groups to see if you can restore the group from there.
Hope the information can help you. And if there have any unclear or misunderstanding, please feel free to post back and we’ll continue to help you all the time!
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