Originally posted by Draconifors:

The boar is too far from where you found it, probably. Every time, after H&H, I've brought a boar from farther than the render distance it's kept running back and forth along the wall closest to its roaming location. Moving the pen wall has always resulted in the boar simply adjusting the spot where it runs.

Really annoying. In my current game I was super lucky and star boars spawned right next my base after I'd built it.

It worked fine prior to H&H.

Yeah I think this makes sense. I did run it quite a while and the direction it's pressed up against the wall is towards where I found it. And moving the wall just moves where he runs.
It was the only star boar my friend and I found after 2 hours of searching. Sadly only a 1 star.
The boars did breed with time, thankfully. Seems the running pattern was unrelated and just made it harder to observe their behavior.
We've kept it. That one is just a bit... Different, lol. It was the beginning of our entire herd so I don't have the heart, and it gives it personality. We named it Hogscotch.