Illy the anointed vanishes

Back from 4 weeks in Africa and the Indian ocean, picking up where I was (and missed the 1st 3 weeks of 10 anniversary stuff).
Getting back to Jacobs manor, and fighting Billy the Anointed.
Took 3 tries because he kept glitching out. The red head marking his location was there, but he was not. Occasional purple swirlies showing where he should be, but he’s not visible. Save/quit/rejoin, he’s back, then glitches again.
3 times until I was able to kill him.
Anyone else have him glitch out of existence?