Drag and drop issues

After looking at your project I too could not get it to work. After a bit of meddling, I wondered if it was your image files. I exported one of the files (first aid) and reimported the file. I noticed it was no longer green but white. I tested the drag & drop and suddenly the image would snap to start if not correct.

I looked at your images and noticed when editing in the states the Normal mode was visually modified. I reset the image and tested again. It still didn't work.

I think your best option is to take the original images and reimport them. Do not modify the colours or add new states. Make sure the images work as is, when testing the drag & drop.

Then use one of the images and make your previous modifications. See if that resets, or not. I'm guessing what ever changes you made have somehow messed with the rest option. So basically make a change, test, make the next change test. See when it fails.