Error: This operation is not allowed, since scanning is in progress.

Using Adobe Acrobat Pro DC v. 2019.021.20061

As of today, when I try to enhance my scans, I get the error message:  This operation is not allowed, since scanning is in progress.

I have no scanner associated with this program.

Tried closing the app and got the same message.

Updated the app; repaired the installation.

Rebooted and still the same message when I try to enhance my scans.

Please help.  Thank you!