I know the issue I just can't provide a fix until I know why you're using those behaviors so when I fix it i'm not actually breaking the functionality of the cubes.
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I do not understand why you have a jumpthru behavior and a platform behavior can you explain that before I change these behaviors?
Could you upload your .capx here. Recreating what you want then trying to fix it will prove difficult without your work to work on.
Pretty cool! Well done.