I’ve been running T3 regularly and backed it down to T1 to fight Lilith. She takes plenty of damage normally until a little past the 2nd mark on her health bar, then nothing. I just pummeled her with so much fire and actually ran out of potions from dodging many rounds of her spikey waves. It was comical. I restarted my game, then verified files and reset all dungeons. No help. She still takes no damage. After having spent over 100m gold I’ve spent my spare hours in the past week earning on a CHANCE of getting a mythic through tributes to the Undercity…for nothing… after this I can see that the game is completely broken. Blizzard is now spitting in the face of those who take time out of their LIVES to try to enjoy a relaxing game - AND HAVE THE NERVE TO OFFER IN-GAME PURCHASES. This needs to be fixed or I am done. The main boss is broken during the BOSS season. Pfft.
I’m having the exact same problem on PC. T3 is easy to handle, dropped down to T1 to fight Lilith, do a whole bunch of damage fairly quickly and BAM! She decided she was done taking damage. I turned on the combat text and can see that I’m still doing plenty of damage, but her health bar just doesn’t move. I’ve even just stood there and maintained my Ice Shield so she couldn’t kill me and still the health bar doesn’t move. So I know it’s not a matter of not enough damage to counter regen. I’d add a screenshot here, but that doesn’t seem to be an option.
Experienced similar behavior in solo & party formats since the bosses changed to mandatory multi-phase – especially when latency spikes.
Yes, it’s a known issue that she is regenerating her health (unless that is what blizzard intended). It’s already been reported.
Do you have a link to where it’s been reported and being worked on?
I don’t have information on whether they are working on it; but its definitely been reported already well in advanced.
Echo of Lilith fight is definetly bugged.
In standard my main is farming T4 with easy, so before trying to beat her in Hardcore for the achievement I put in softcore T1 and went to try her. I can down her HP to 1/3 and then the fight get stuck in a loop, she doesn’t change phase and if I keep rotating my cooldowns I won’t die even taking her moves.
So, becomes a null fight, neither will die and neither will win.
Glad I tried on softcore before burn my chance on hardcore.
Same issue, I am playing on t4 and clearing 75+ in the pit. I get her down to 33% and she goes immune until I oof myself in the swirls.
i can confirm this bug is currently active. Same issue. I get her down just fine until 33% and then she takes no more damage. I see Billions of damage, but her HP bar wont move. She will keep doing her wave-attack mechanics until i just give up and walk out of the circle to die.
On a sidenote… who’s briliant idea (NOT) was it to not let us use Town Portal in bossfights???
Scroll of escape… Try it next time 
Offtopic:
They dont have that on normal. I meant it as follows. You end up in a bossfight that bugs. The only way out is to either die or try a log-out. Which in both cases is stupid. There should be an unstuck option in case a bossfight bugs.
Like in some dungeons, when you kill the boss too fast, the dungeon will not register the kill and you just stand there like a sack of 
. Cant die, cant teleport out. Logout is the only option then.
But on HC i can understand a scroll of escape.
Sorry, didn’t know scrolls were not in normal. So it’s stoopid for nrmormal players not to be able to leave. It’s stoopid too for HC players to leave the fight though
Yeap, get’s stuck at around 33%. Came looking for this.
Same here. How am I suppose to get the boss power or the achievement? Eager to hear from Blizzard on this matter. Always bugs at the same amount of life left; about 33%. So tired of Lilith bugs… When will they finally fix this?!
Appears to happen when switching torment levels, have no issue when doing T1 repeatedly then going back to T3 but then when going back down it bugs.
I had also a bug when switching. It killed my hero.
Edit: someone on reddit answered it for me. She was bugging out because I was doing too much dmg. T1 & T2 as a singleplayer bug out for me. T3 bugs out in a multiplayer. But, T3 in a singleplayer does not have this issue. If anyone’s interested, I’ll paste the link to the reddit post.
I didn’t see this post right away. I made my own post about it today. I guess it’s not something they’re gonna fix. I even gave them a link to a reddit post I made with a video of what happens in the fight… I really hope it doesn’t carry it into the next season.
Still having this issue in Season 9.
I’m having the same issue on PS5
I killed Lilith 12.5 hours ago and now tried in 4 seperate games and once she gets to about 42% she takes 0 Damage