Teleporting Merc + Monster AI Issue

[Smoketest]

A merc will 'teleport' next to you if they become stuck on the scenery or otherwise fall too far behind us as we are playing. However, I've noticed that sometimes when they do this, the monsters will proceed to ignore them, as if they aren't even there, and will come straight after me. The merc, meanwhile, goes on attacking monsters just fine.

Taking a portal or wp or just running into town fixes the problem.

I specified realm games because I haven't noticed this behavior in my singleplayer games. It could be a latency issue.