None of that worked for me, so I started over from scratch, and imported screens & copied blocks. Tiresome but it worked. I did, however, run into the same problem, but after building the project every 5-10 minutes, I was able to isolate when it stopped working and back up a few steps. I’d say compiling often is a good way to ward off future AAPT failures. BTW, some sort of undo would be a great addition to the project. Not complaining, I think Kodular is great!