Dialog box does not accept input, stays on-top and hides everything under it. Ubuntu 20.04

Upon rebooting, I get dialog box

Authentication Required
Authentication is required to start 'cups.service'. 

I can type in the password and click Authenticate, but then nothing happens. I can't see under the box. I can't move the box, can't cancel the dialog.

But, I can click on where I know the underneath icon to be and that click is accepted and the program in question runs.

Thank you in advance ...

I have recently done a clean install of 20.04.

2 Answers

From the comments in the bug linked in the other answer, the following seems to get rid of the window , though I have absolutely no idea what actually is happening under the hood:

"And when I press ALT+F2, then type "r" and press enter, it's gone!"

This is a known issue. When I reported the bug, this was the reply:

* This bug is a duplicate of bug 1824874 *

Thanks. That confirms this is a duplicate of bug 1824874.

** This bug has been marked a duplicate of bug 1824874 undismissable, unclickable authentication dialog left on screen (top-left corner) after policykit authentication [pushModal: invocation of begin_modal failed]