This has been posted about before here, but that issue is marked as fixed, and the bug is still happening.
It happened to my dreckos in the attached save. There wasn't a critter getting stuck, just no critter responded to the rancher's call. The rancher kept calling until I saved/reloaded. It worked properly after reloading.
Spaced Out DLC, Build U49-577063-5.
Bug occurs unpredictably and without any obvious trigger.