'Drag Over' state wont reset (File Attached)

Hi all! 

I seem to have a problem. I've setup a drag and drop activity where users just need to drag words to one of two options. I applied a 'Drag Over' state to the drop targets. This is just a simple outline appears on the drop target. This seems to work up to the point where the drag item is dropped incorrectly. The item snaps back to its starting position, however the drag over state of the drop target remains. 

For this example, drag the first option 'obligations' onto the 'Not Covered' box and let go. You will see it applies the drag over state to Not Covered, but this doesn't reset when I let go of Obligations. Obligations correctly snaps back, but the drag over state remains. It does however correctly switch on and off if I hover the drag item in and out of the drop target and don't let go. 

The only way it resets is if I drag the snapped back item back over the drop zone and out again. 

Is there a way to make the drop zone state reset to normal when the item is dropped incorrectly? I'm guessing triggers could solve this, but I just wondered if there's a quick reset switch/button I may have missed somewhere? 

I've attached the file if anyone is able to help. 

Thanks!