Animals "roaming away" inside of their pen? 1.3

[Orch10]

I'm not sure why there isn't a general "help me" sub forum on this website, but I suppose this one suits my question best.

I'm getting notifications in the top left of my screen reading "___ has started to roam away!" yadda yadda, and when I check on the animal, they're doing nothing other than moving about within the pen. The pen is fully enclosed, is properly set up to allow all animals, and has sufficient nutrients within to satiate them all. They have a sleeping corridor and a storage room for their hay, all with straw flooring. Some of the walls of the pen are not fences, but instead a rockface or stone walls, which hasn't been a problem in the recent past with my testing of the pens. Yet, my animal handlers will rush to the pen and rope them to a spot maybe 5 tiles away, and that counts as them being roped "back to the pen" that they're already stuck inside. What is happening, and why? If you really need a screenshot of my pen, I'll provide one but I dont think it's necessary. To clarify, the pen is fully enclosed. I will include a screenshot of the mods I have enabled.