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.
I do not understand why you have a jumpthru behavior and a platform behavior can you explain that before I change these behaviors?
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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.