This is one of the cases where we sacrificed compatiblity for a bug fix and for our support's sake. Wrong collision boxes of large models are a frequent beginners' problem. This is gone now, and for this we accepted the incompatibility. You can check your bounding boxes by pressing F11 twice, and should be able to fix your script in 2 minutes. Correct movement code, as in 99% of all levels, will still work as before.