Actually, mine isn’t changing anymore. Same new firmware that caused the issue initially, but it just doesn’t require the code to change. The problem may be in how we are setting it up. But now, its working normally for me. I did have the issue initially, but I stopped requesting refreshed codes and it works fine.
I’m not sure, but I think when it started for me I needed a new code for all my devices. I couldn’t just enter the code that was there for some reason. It wouldn’t give me the “Ok” prompt to accept the code unless I asked for a new code, for the Bambu Handy app. The printer would hold the code (whether I turned it off or not) as long as I didn’t request a new one, but the only way I could get the phone app to accept the code was to request a new one. I fixed this by not requesting a new code, and re-installing the phone app. Then it allowed me to enter the IP and access code without refreshing the code. And its worked cleanly since.