Can't play in snapshot

I’m trying to load into the world in copy.zip while in the new snapshot, but I keep getting the message “invalid player data” after the loading screen. Originally, I thought it was an issue because of player effects from beacons or conduits, but after loading into the same world from 1.21.10 and moving outside of the range of the beacon, I still can’t open it from the snapshot. My other world opens just fine in both versions.