Dialog box won't appear / invisible - Windows 10

There are multiple dialog boxes that don't appear or won't draw.

The latest one came after a catalog backup.  My catalog is big, so backup takes an hour or more. During the backup, the computer timed out and locked the screen.  Upon return, the Elements Organizer screen was unresponsive because there was an open, but invisible dialog box.  Windows status bar showed that there was an open dialog box, but there was no way of displaying it.

This has happened on several occasions, not sure it is because the screen locked or because the organizer drew the dialog behind the active window.

Running Windows 10 home, 64 bit

main screen is 4k running at 150% scaling. Secondary screen is 1080 with 100% scaling.