Can’t say I’ve seen that, but anything is possible with this marvel of design >_<
Did you use the ‘safe’ spot at the back? I’ve only used it once and thus have little experience to draw on, but it might count as outside the arena, causing him to reset. (He probably learned that one from Terra.)
A shock Lady Fist can work wonders. Depending on your level, a powerful Tesla (preferably a Storm Front) can be great for when his chest opens.
I haven’t gone back on OP levels because I cannot be bothered, so may need to take that with a whole bucketful of salt.
Axton’s turret(s) may cause him to glitch up on the ledge, and Deathtrap has a very high chance to do so, so beware.
Of the standard bosses I still dislike BARex more, but it’s a close thing.
Edit: Ooops, almost a necro. Sorry about that.