When playing the Witch Doctor and fighting Adria in Act 5, she won’t reappear when doing her disappearing trick if you’re using Spirit Walk at the time… until you step out of it.
I have “Shukrani’s Triumph” equipped, so Spirit Walk lasts until I use any attack three times. As Adria disappeared, though, and her maggots can’t be attacked, I just ran around as there’s nothing to attack and nothing happened for a good thirty seconds.
The first time I thought my router might have disconnected, which wasn’t the case. Only after this happened the second time, I’ve noticed that both times I was spirit walking.
While this might be intentional on some level, there should be a timeout, as it was by pure chance the first time, that I threw some attacks into the nothingness and jumped out of spirit walk, so she could reappear.