Creatures Caves

I currently have 5 Norns and a Grendel. They all go from 1 hour 30 minutes alive to 3 hours. (They were pettted every time I asked them to eat and they did.)

Sometimes, none of them do as they're told for like 15 minutes if not half an hour. By that I mean I tell them to eat, they approach the fruit, look a the fruit, they retreat from the fruit, then approach the fruit again, then walk around while looking at the fruit, then come back to the fruit and STILL DON'T EAT IT. Including ones who normally eat when I ask them to. Sometimes it's just one of them being stubborn, sometimes it's all of them one after the other who just refuse to eat.

Any tip on what to do when none of them is willing to do more than stare at their food for what feels like ages?