Thanks for testing it out!
Yes, it's true that it gets repetitive after a short time, even though the time to the next platform closing can be 0 seconds. (Random time from 0 to 2.5s)
The bug is new to me. It sounds a bit like that you have to jump really precisely to get to that, because otherwise the Physics Engine of Unity should make the cube fall over.
I hope I can fix that problem :)