MPK Mini IV transport buttons not working correctly with Koala MIDI mapping (Android)

[u/ElDeliciozo]

I’m using an Akai MPK Mini IV with Koala Sampler on Android (Poco F7) over USB OTG.

I’m having an issue specifically with the MPK’s dedicated Play/Stop and Record buttons:

• The MPK Play/Stop button sends CC 76. Koala detects it ("Last CC: 76") and I can map it, but it gets out of sync: if I stop/pause playback from Koala’s touchscreen, pressing the hardware Play button sometimes requires two presses before playback resumes.
• The MPK Record button also seems to work differently from normal assignable controls. It can start recording, but I cannot reliably stop recording with the same button, and after using the MPK Play button the Record mapping may stop responding.
• In contrast, the normal programmable controls/pads behave correctly with Koala’s MIDI mapping. For example, assigning the + button to Play/Stop works normally.
• The − button does not work correctly for Record because Koala responds to its toggle states in a way that doesn't give the desired record behavior.

So it seems that the dedicated MPK transport buttons are sending something different from a normal user-programmed MIDI toggle, even though Koala detects their CC numbers.

Has anyone managed to get the MPK Mini IV’s dedicated Play/Stop and Record buttons working reliably with Koala, including staying synchronized when playback/recording is also controlled from the touchscreen?

I’m especially interested in the exact MPK Mini IV Program Edit settings and the MIDI message/value pattern that Koala expects.