I have also experienced this problem and came here to report it. Playing on Nintendo switch. I have the turtles in an enclosure with an automatic collection system for the scutes. The system is pretty much pointless at the moment because as soon as I leave the enclosure any turtles not nametagged (adults and babies) will instantly despawn. Once I only went into the adjacent building to stamp a nametag and the adult and baby turtle were gone when I reentered the enclosure.
I have also experienced this problem and came here to report it. Playing on Nintendo switch. I have the turtles in an enclosure with an automatic collection system for the scutes. The system is pretty much pointless at the moment because as soon as I leave the enclosure any turtles not nametagged (adults and babies) will instantly despawn. Once I only went into the adjacent building to stamp a nametag and the adult and baby turtle were gone when I reentered the enclosure.