devtrackers.gg
I suspect its worse; that an impasse has been reached. That the delay in ignite applying is caused by the server not wanting to blindly allow for damage which would kill the targeted boss if unchecked.
My theory, having seen none of their code:
The game attempts to check to determine if the damage is real, putting all damage on hold, but by the time it figures out it is real, a new ignite has been applied.
Only one ignite can be on a target at a given moment, and the one picked is the bigger one. Since the second ignite has not yet been evaluated, no ignite is applied because the game doesn't know which is bigger.
Then, the second ignite evaluates and a third ignite is applied, but the first ignite has already expired, and the same scenario ensues. Infinite loop of zero damage.
This theory holds up in that the threshold for doing zero damage varies based on boss life. You can run into this wall very early with weaker bosses. If I attempt to run T1 maps, I can cap with no damage supports.
The real problem is that this type of checking to make sure a corrupted data packet doesn't instantly kill a boss is probably a good idea for GGG to have in this game. They just need to change something more nuanced in how it is error correcting/checking and have it not eat into ignite duration and/or just apply and then override the ignite after checked instead of trying to compare and getting stuck in a zero damage state.
Ultimately, too much work for GGG. They'll probably nerf the skill to fix the problem at the end of the league and never actually address the interaction past investigating it.
I'd just like to say at the risk of sounding ego-maniacal, I saw this coming the day the gem info was posted.
Edit: Fixed image link.