Saresh disappearing mid fight and never reappearing

fought the boss twice and as he attempts to go into his immunity phase for his slam, he disappeared from the arena. I attempted this fight twice in a row and had the same issue. I noticed that I had damaged him past the immunity phase threshold for his health compared to previous attempts, this may be a cause for him to not reappear.

I have had the same issue just now. Just curious if there is any workaround?

Just ran into this issue.

same, so sad