I hate it! Autodesk should work on this problem! Booleans suddenly don´t work when Geomitry is too Tricky! I had the same problem and I asked in a similiar thread about that topic, and everybody get lost when they road booleans! Try to booleans 2 cubes in your frog scene and you will see that it works, but on your frog not. I hope that anybody else can help you, but I don´t think so! Probably you must remodel everything and do booleans a part bevor! Sorry...