Situation:
Drag and drop will not move message to another folder (sub-folder of Inbox).
It was working the day before.
Copy and paste message does not paste.
Using menu commands to move message does not move message.
For what it's worth, a solution (two) were found. Below is a summary of solutions found on the 'net and what did not/did work...
Using Esc once or multiple times still does not allow move message.
Exited Office apps.
Use Apps & Features to run on-line repair of office.
Repair did not fix moving messages (AKA drag & drop).
Confirmed WebMail can drag & drop messages.
Uninstalled Microsoft 365 (Microsoft 365 Apps for enterprise - en-us.
Restarted laptop.
Installed Microsoft 365 via WebMail > Microsoft 365 > Install Apps > "Microsoft 365 apps" (Includes Outlook, OneDrive for Business, Word, Excel, PowerPoint and more.)
Outlook still cannot drag & drop (move) messages.
Signed out of office and messages still cannot be moved.
Ran Outlook as admin but it never stopped saying "setting up", so gave up on that.
Found that Folder View allows messages to be moved, however user prefers regular message view so changed it back.
Exit Outlook. Delete user's OST. Start Outlook and now messages can be moved.
I did NOT try creating a new Outlook profile, although I expect that would work as I assume a new OST would be created, which would have to be rebuilt.
Did NOT try turning off cached exchange mode, but I would have expected that to work as it bypasses the OST file, making it work more like web mail. However, the user is often without internet access so no OST would not have been practical.
The problem with deleting the OST is that it needs to be rebuilt which can take time. You might try using scanost.exe, however that no longer exists in "C:\Program Files\Microsoft Office\root\Office16" (W10 22H2), and back in the day, scanost may have taken as long as rebuilding the OST. Maybe that's aother reason why it's no longer available.