I noticed that when I step through a melody with the arrow keys to audition it, when the note I’m playing has a System Break attached to it and is not the very first note of the flow, the playback and selection jump from the first note to the system break marker, and over the next note to the third, at least in my example here, see the gif.
This is not a bug, but rather a consequence of the design of the arrow key navigation, which my colleague András explained here.
Well, okay- thinking about the concept of arrow-key-navigation here, I can even manage to jump to the second note in that system. However, hitting down-arrow from the flag to the note and then right-arrow again to keep on stepping through the music is not really intuitive. Plus, this is the second system, it does NOT happen on the first system (even though that system has a System Break flag right at the beginning as well, because I used Engrave mode to make twelve whole notes into one system). On the first system, to get to the flag, I have to press up-arrow from the D (regardless of octave).