mGBA but it also happens on hardware GBA, don't think it an emulator issue
Viewing post in Tremblay Island jam comments
You were right. What happened was that I had made some engine tweaks to Butano itself, and for some reason, when I made my latest build, it seems to have undone those changes. I went back in and fixed it, and it's working now! I've uploaded the latest working build. Fingers crossed, I've only done a little bit of testing so far.