Entering notes fails

I installed MuseScore 4.1 a few days ago and went successfully through the basic steps of entering notes in simple scores, until this afternoon. Because I consider myself an absolute beginner with this software, I ran several tests doing the same sequence of operations, to ensure that the cause of failure was not my lack of skills. In the end, I got into the following utterly basic script leading to the failure.

Step 1: create a new score (C major 4/4); result is shown in screenshot 1 below.
Step 2: selecting the starting point for entering notes (and rests) at the very beginning of the score (see screenshot 2)
Step 3: select note entry mode using the pen icon on the keyboard (see screenshot 3)
Next steps: enter notes (and rests) using keyboard icons (various durations); none of these actions were successful (no note appeared, no rest was added); I ended the input attempt by pressing "ESC" and tried the same thing by using the keyboard shortcuts; no notes/rests appeared;

In the end, again in input mode, I clicked on "+" followed by clicking on a "C", "D",... selections (as shown in screenshot 4) and these operations were successful to my surprise.

Can you please evaluate if this is a case of a software malfunction and if so, tell me what to do to repair this.
I run MuseScore 4.1 on MacOS Ventura 13.4