Idk if it bombed, it sold and reviewed really well (it helped that it was in stark contrast with Anthem which also released around the same time), but they sort of forgot a lot of lessons about the endgame from the previous installment, so the community fell off a cliff a couple of months later.
It's a much better game now, but people are slow to come back.
That's something i really enjoy about Ubisoft. They don't just stop updating and creating stuff for games that underperformed.