Hi @Ryan Graham ,
I tried searching a lot but didn't find any official document explicitly stating if this is a limitation in V3. I've tried submitting feedback for your post below the documentation and we can see if we can get any more information there.
https://github.com/MicrosoftDocs/office-docs-powershell/issues/10907
Meanwhile, if you need to use "Get-user" urgently, you can uninstall the V3 module for the time being and install the old version V2.
Best regards
Shaofan
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