[mcrossy]

So what's the easiest way to reproduce this issue? Just continue adding smart buttons tied to MIDI commands until the top of the overlay disappears and doesn't come back?

Exactly, I add buttons on various pages (with the top overlay always present); when I've finished button editing in a song, I click on "Save and continue to next song" without closing the Smart Button dialog, and after some times, at a certain point (random), the top overlay disappears.
I haven't checked if in that case the option of "Always Show Title Bar" has gone OFF by itself, but surely before it was ON, because it's one of my preferred settings.

Do you have "Always Show Title Bar" enabled in the settings?

Yes, since the 1st day I kept this setting ON.