Yep you're absolutely right now that I test it. I just uploaded a patched version of the plugin, can you download that and see if it fixes the issues on your end?
Viewing post in Side View Enemy Health Bars Plugin for RPG Maker MV comments
Here's some background info that may help. The plugin iteratively checks each enemy during a screen update. You can access each individual enemy object with this code, where i is the index that the plugin uses to iterate:
$gameTroop.members()[i]
As such there are tons of different ways to show or hide the HP bars for each specific enemy in each scenario. For example, this is a condition I use (in addition to some others):
$gameTroop.members()[i].isSelected()
This checks if an enemy is being selected by an attack, skill, spell, etc. If you wanted to only show HP bars for living enemies, try this:
$gameTroop.members()[i].isAlive()
This method does exactly what you think it does, and only evaluates true if the enemy is still alive.