@Mathisj, Thanks for posting in Q&A.
From your description, I know that the new Outlook does not work in the WIP policy.
Based on my research, please make sure that the new version of Outlook information is configured correctly in the WIP policy.
The following link contains detailed information for you to refer.
Non-official, just for reference.
https://techcommunity.microsoft.com/t5/microsoft-intune/wip-policy-for-outlook-client/m-p/2160245
Note: Windows Information Protection is being retired by Microsoft and won’t be included in newer versions of Windows. The official replacement is Purview Data Loss Prevention.
Hope above information can be helpful.
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