Tomb of Terror Boss restore its health to full if you can't kill it

Wing 2 - Heroic Mode

I put the final boss down to around 100HP and died. Next time meeting him, his HP was restored back to 300.

Same situation. Wing 2- Heroic Mode. At the first try, I’ve put the final boss to 56 HP.
In the next run I’ve left him 37 HP but his health has been restored to 56.
And the last time he was on 7 hp - and - surprise - again returned to 56.
I’ll not waste my time on a dungeon run until this bug is fixed, as the progress is not being saved.

Same thing is happening to me too. I’ve brought him down to 150ish two times in Heroic and died. Then he restored to 300 health.

Same issue. Only first time counted. His health keeps returning to 36. Wished they fix all this crap before sending it out and saying it’s your problem now.

Similar issue, but Wing 1 Normal. Previous run, brought the PL down to ~180. Second run, got him down below 100 because his hero ability changed to Murlnado. Now the title screen for the wing is showing his health as 181.