I've been having a blast with the game so far, but unfortunately I had a pretty bad glitch happen the last time I played. I'm supposed to be relighting the fires in the towers of the forge of Hephaestus. I got there early and lit one before I had the quest, but then stopped because I figured I'd get a quest for it later, and I know how sensitive Ubisoft games can be to that sort of thing, and I didn't want to tempt fate.
It seems fate was already tempted though, because I went back after getting the quest, and now one of the towers simply disappears when I get close to it. From far away everything is fine, but as I get closer and I assume the tower has to switch models for the LOD system (?) it simply doesn't load in, so there's a vacant spot where the tower should be.
I haven't reloaded the game since it happened, so I'm still hoping it'll be fixed upon restart, but if it isn't, that's a progression blocking bug.