So, I found a black cat and brought him from quite far away (I walked him about 2000 blocks in the nether to get him home).

Anyway before I was able to get him through the nether portal at 0,0 where my home is, he jumped up on a chest. I left him overnight, and when I came to get him I cannot make him un-sit, I cannot drag him with a lead, and I cannot hit him to make him stop sittiing.

Furthermore, he will still move! It looks like he's dragging his butt on the floor as he's still in the sitting position, but he won't follow me at all (even with fish). Somehow he is still able to get up on boxes some times.