If mesos are not exploding but still dealing damage, please pick up some scattered mesos (eg mob dropped) until mesos disappear upon using the skill. If mesos do not disappear with mesos explosion, the killed monster does not drop items or exp. I said that assuming you killed it with mesos explosion.
Also consider reading this: https://royals.ms/forum/threads/glitch-abuse.186416/ You should be fine as many new shads aren't aware and its a glitch that hasn't been fixed for years, but make sure not to abuse it.
ty for sharing! btw i do not use the mesos bug , i think this bug is probably caused by the mesos dropped when killing elderwraith.
Happened to me as well. Recently I killed many BFs (think 15-20) and it happened twice. My pets pick up mesos from mobs (Elderwraith) which I guess might've helped cancel the glitch without me being aware or taking any active action, but the chance to have it happen exactly as you last-hit always exists... maybe like 10%? From now on I'll last-hit with Bstep, but for lower level bandits it might be a problem.