Ok so I originally posted a fix which was down to OneDrive causing the issue, but then the issue came back and it was only when Outlook was open.
I made a GPO which turns off Win11 Explorer and changes it back to Win10 if anyone is interested just amend the following keys and restart Explorer:
Enable Win10 Explorer
[HKEY_CURRENT_USER\Software\Classes\CLSID{2aa9162e-c906-4dd9-ad0b-3d24a8eef5a0}]
@="CLSID_ItemsViewAdapter"
[HKEY_CURRENT_USER\Software\Classes\CLSID{2aa9162e-c906-4dd9-ad0b-3d24a8eef5a0}\InProcServer32]
"ThreadingModel"="Apartment"
@="C:\Windows\System32\Windows.UI.FileExplorer.dll_"
[HKEY_CURRENT_USER\Software\Classes\CLSID{6480100b-5a83-4d1e-9f69-8ae5a88e9a33}]
@="File Explorer Xaml Island View Adapter"
[HKEY_CURRENT_USER\Software\Classes\CLSID{6480100b-5a83-4d1e-9f69-8ae5a88e9a33}\InProcServer32]
@="C:\Windows\System32\Windows.UI.FileExplorer.dll_"
"ThreadingModel"="Apartment"
Re-enable Win11 Explorer
DELETE HKEY_CURRENT_USER\Software\Classes\CLSID{2aa9162e-c906-4dd9-ad0b-3d24a8eef5a0}
DELETE HKEY_CURRENT_USER\Software\Classes\CLSID{6480100b-5a83-4d1e-9f69-8ae5a88e9a33}