Trigger collision not detected if player is stationary

I have a trigger collision between my enemies and my player. I move my player using the accelerometer so when testing on android this isn't an issue as the player is constantly moving and everything works fine.

Just recently though I noticed when I tested something in the editor that the enemies just circle around my player until I rotate him in the editor. It causes this effect:

They'll just keeping going around in circles until I move the player and then they'll be destroyed. Like I said, this isn't an issue on android, I'm just curious as to why this might be happening?