We were fighting the Bloodstone Crazed shark boss in Bloodtide Coast, and still had ~10 minutes on the timer, when the boss just disappeared.
What I suspect happened is that the boss rotation changed (in this case, I think to the “break” portion as the Levvi’s Detector didn’t do anything when I clicked it, which is some some pretty unclear messaging) and as a result it despawned our boss.
Either it needs to be clear in-game what the cyles are for the bosses, or any spawned boss needs to last its full timer. It’s bad enough that if the cycle changes while you’re hunting mobs you’ll never know until you realize it’s been way too long.