Debian simple-scan inoperative shortcuts – Super User

I installed Emmabuntus (Debian Buster based) on an ordinosaur computer with LXQt as DE. The simple-scan application v3.30.1.1 is installed by default and works, but the supposed shortcuts ctrl + f and ctrl + m that greatly simplify the scanning task are ineffective. Nothing is happening. The shortcuts seem to be “hard-coded” in the application (they are given from the “Keyboard shortcuts” menu and I couldn’t find a config file).

How do I know if the problem is with the application itself or if the system or DE (or whatever) intercepts the shortcut before the application ?

How to make these shortcuts effective ?

Thank you in advance for your expert advice.