This happens every now and then, but definitely enough to be frustrating. It happens on both iPhone 11 Pro and iPhone 12 Mini. It happens more often when I'm being chased down by enemies, but I think it might also happen without enemies, but less frequently. I typically just do a quick save if possible before changing areas as a safe-guard. The most frustrating is when it happens after exiting a cleared dungeon. Game is great so I'm still playing but thought I'd give a heads up since updating an iOS app is so easy and painless .