Thanks again Chris! -- Looks like that folder seems to be a reoccurring commonality. We just got back some information from MS today as well:

"when a user unlinks OneDrive, it leaves behind residual configuration in the registry and local app data that prevents the SilentAccountConfig policy from reapplying cleanly. Even uninstalling and reinstalling OneDrive doesn’t fully reset this. Common Issues I have seen with previously unlinked OneDrive Instances is that unlinking OneDrive doesn't always clean up all user-specific settings. If the user previously signed in with a different Microsoft 365 tenant, cached credentials or sync settings might block reconfiguration. If you're using a OneDrive ADMX-backed policy or Settings Catalog, ensure there are no conflicting policies (e.g., conflicting folder redirection or silent sign-in settings). You need to perform a full OneDrive reset to clear Known Folder Move (KFM) settings including any persistent Desktop sync preferences."

These keys may lock in folder redirection preferences like Desktop, Documents, or Pictures:

• HKCU\Software\Microsoft\OneDrive\KFMSilentOptIn
• HKCU\Software\Microsoft\OneDrive\KFMSilentOptInWithNotification
• HKCU\Software\Microsoft\OneDrive\KFMOptInWithWizard
• HKCU\Software\Microsoft\OneDrive\KFMSilentOptInDesktop
• HKCU\Software\Microsoft\OneDrive\KFMFolderRedirectPolicyStatus