Enemy "Disappears" on Death

[FragdaddyXXL]

Also, I have one more issue where I have an area set to make an entity active and play a sound when the player walks into it, and if I go to a different map and then back, the entity is still there, but the sound plays again if I walk into the area; this problem is not seen if I don't leave the map (the area deletes itself like it should).

Did you place the callback for that area in OnEnter()? If it is, place the callback in OnStart() instead.

If you really want it foolproof, create the callback after the player does something (pick up a key, etc.) and have that something be only done once. This may or may not be possible for your situation.