This is a guess on my part, but it might work.
But if you type in a URL “beyond” the login screen URL, like this:
https://example.com/wp-admin/plugins.php
Well, it puts you through the motions of logging in again, and then seems to let you through. Not sure why, though. Mind giving it a try?
Andrew. I have just deactivated site brains from my plugins, as this was causing an issue with my light box and reapplied your suggestion. This seems to have worked!! Not sure why…
Thank you very much for replying to my post.
All te best,
Joyce