It’s not possible to run an AppStudio app without all the files it uses, so I wasn’t able to open this project.
Can you create the absolute smallest project that reproduces this problem? Take out everything that isn’t needed to make it happen. It’s the first thing I would have to do here, but since you know your program inside out, you’ll be able to do in a fraction of the time. What sometimes will also happen in this process is that you might find there is a problem in the code after all.