Sonar Artist Piano Roll not working after editing 3 or 4 notes

I just bought Sonar Artist (v22.11.0 build 111). I used to have a free Cakewalk Sonar LE that came with my Boss effects pedal for guitar. That version is discontinued and no longer works on Win10.
 
The good thing is that I can open my old projects without problems, but I tried to edit a MIDI track in piano roll (which is by far not as good as the old LE view) and after editing only 3 or 4 notes, the F8 / F9 keys seem to switch between edit / draw mode, but the mouse cursor changes to a vertical resizer and I can't edit/insert any notes with the mouse anymore. Is this a know bug? Am I doing things wrong?
 
Frankly I get the impression the product has got worse in a few years. And, it's weird that the version I got as a bonus with my fx actually worked better than this paid version. I'm a bit worried I did the wrong purchase.
 
Any help/comment is appreciated