Music Tech Help Guy demonstrates a Logic Pro quirk with unquantized MIDI recordings: notes played slightly ahead of the beat won't sound if your playhead starts after their note-on message.
The fix is MIDI Chase, found in File > Project Settings > MIDI > Chase. Turning on notes (and no transpose instruments) makes Logic play any note the playhead lands inside, no matter where it starts.
It's a project setting, not a global one, so it needs to be enabled every time you start a new project.