Hey! - I’m playing S26 as a FireFlame wizard, and noticing many mobs, including elites lives on 1hp and the don’t die. It happens very often. Which is pretty annoying when pushing GR.
This is one of the oldest known bugs in the game. There are certain builds/play styles that seems especially susceptible to it. The only known workaround is pulling the monster(s) far away from Urshi then finding a different way back to her. Homing Pads on your companion are useful but then you might need to walk all the way back from town to get to her.
I am having a heck of a time on my HC Barb with this bug, I seems to be happening a lot more this season to me. I might have had the issue in previous seasons, but it is at least 1 out of every 3 GRs right now that I’ll get some leaping mob usually. I have been running the Wastes set. I think I’ve had one elite mob, but it has been 95% any mob that leaps for me.