Outlook O365 – minimized window issue

Had an issue today with a user using O365 Outlook. Whenever they tried to open a message in a new window, it open it as a minimized window, showing only dots, then the minimize/full screen/close window icons.

I could use the “windows key + [ARROW]” buttons to move and essentially resize the window. But after closing and re-opening the message, it was the minimized window as before. I tried resizing it and holding “SHIFT” when closing the window, but that didn’t work either. Everything i tried basically wouldn’t persist. Every time i closed the window and reopened it, it would be that same minimized window.

What did end up working for me was to close Outlook, and make a registry edit. This is the registry key I deleted:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Message\Frame

After that, opening messages in a new window worked as expected again.