MIDI instrument keeps changing while playing region

I have a MIDI track that plays, but I’d like to change the instrument - normally a pretty easy process. I’ve tried both the ACE Fluid Synth and the General MIDI Synth and it happens with both. Halfway through playing the region - the instrument switches back to what it was before.

Is the instrument information stored in some other place that might be overriding that setting?

I’ve tried making a new MIDI track, copying the region, unlinking it, then changing the instrument, and it still flips back to the original instrument. Maybe it’s a bug?

Chances are you have a program change recorded in the MIDI region.

https://manual.ardour.org/working-with-midi/patch-change/

That was it - I’m not sure what a patch change is, but I had them in there. Thanks for the tip. I’m good now.