I had an odd incident last night while running Halatali Hard Mode. I was running it as a summoner, and the other dps in the party was a summoner as well. We were fighting one of the trash mobs (unfortunately, I don't remember off-hand which one, though I think it was one of the gladiators in the stretch before the final boss fight), and only one of my dots landed. So I recast the two dots that missed, and only one of those two landed. I recast again, and the missing dot still didn't land.

Meanwhile, the other summoner in the party didn't appear to be having any issues with his dots.

The most likely culprit seems to be an accuracy problem, since the other summoner was able to get his dots to land. But I regularly run Coil, and currently don't have any issues landing dots in there. If it was a problem with accuracy, then it must have a pretty high softcap. And I more than likely had a string of unfortunately RNG results when determining whether my dots would land.