While playtesting some updates that I'm making to my Doom addons, I noticed a MIDI music playback issue:
Restarting the current level stops MIDI music playback, restarting the level once more reenables MIDI playback. The pattern continues while reloading the same level.
The issue is triggered upon restarting the same level from the main menu (e.g. E1M1, E2M1, MAP01), via savegame or using the "warp" command. Doom, Heretic and Hexen are equally affected. I just tested several builds and found the issue to occur starting with build 2863, earlier builds are working fine.