What platform are you playing on? Can you, per chance, share your save file? I don't think I ever heard about bug like this, so I very curious to find out what might cause it.
I play on Android. It's for sure the first time any glitch like this happened for me. I binged through it to see if beating it again fixed it...it did not. Unrelated note, LOOOOOVE the Halloween event stuff. Need more ice dragon bussy in my life. I have to figure out how to find the save files. But it does let me keep the gallery stuff. Thankfully