@Jodrell at PI
Thank you for your post and I apologize for the delayed response!
Based off my research, I wasn't able to find anything easier than what you mentioned when moving Microsoft Defender ATP workstations from one tenant to another. However, I'd also recommend reaching out to our Microsoft Defender for Endpoint experts within their Microsoft Defender for Endpoint Tech Community page so they can take a look into this issue as well.
Access the Microsoft Defender for Endpoint Community Center
If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.
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