Drag and drop not recognizing the correct answers

There is an old saying in the theater: "Anyone who puts kids or animals on the stage deserves what happens to them." That means that no matter how well-behaved, or well-trained you think they are, at some time they are going to revert to their true nature, and you can only hope it doesn't happen during a performance.  The SL correlation is: "Anyone who uses groups deserves what happens to them." That means that no matter how well-behaved or how well-trained you hope they are, groups don't play nicely with anything, and especially not states, clicking on,  and triggers. Sooner or later, you are likely to have problems with them.

My advice is to save yourself some heartaches. If you like the appearance you have, delete the rectangles, and give the pictures outlines. Or, ungroup, cut the picture, edit the state of the Rectangle, and paste the picture onto the Normal state. Either way, they look the same, but act the way you think they should.

The second and succeeding attempts register correctly if you drag only some of the correct answers. They don't work only if you originally drag incorrect answers. There triggers are the reason why:

Drag and Drop registers the position of an object only if the user clicks it, and drags it. So as far as the system is concerned, all the objects are still within the drop target.  See the video.