Maybe I'm only noticing this now because I recently TR'd (wizard to artificer), but I've been seeing consistent misbehaving pathing with mobs and the artificer pet. Specifically, both seem to forget that you have to go around a corner rather than through it. In addition, they seem to have forgotten how to use ramps; instead of finding the base and climbing up, mobs either walk under or faceplant into the wall that supports the ramp. Similar problems occur with alcoves, jutting pillars, etc.
While this is great for a sniping build, it's somewhat irritating from a gameplay perspective.
Anyone have an idea how long this has been going on? I didn't notice it prior to U31.1, but as I said, I did just TR.