To answer your questions
1) Very short, just a few letters
2) No any QSO shows this behaviour
3) Just the same for any band. I tried it on 15, 20m and 60m with the same results
4) Yes, the note is added but in some seemingly random cases only after receiving the warning an attempt to add a note to another QSO is thwarted due to all of the right click options in the Notes window being greyed out.
5) Recalculating stats has no noticeable effect, before or after the warning is received.
6) Yes, adding a note to a QSO in progress behaves quite normally, the note is saved, and can be edited or deleted. While doing these tests I noted that again, on seemingly random occasions after editing or deleting a note any attempt to add more notes to that or other QSOs is impossible due to all of the right click options being greyed out. Re-starting the programme restores this functionality.
7) I have two Logger32.ini files for two different configurations. They both show the same behaviour.
8) I don't know if this is relevant but if I select a QSO and then open the Notes window all right click options are greyed out.,
I can't think of anything else - if I do I'll add it to this thread...