This is really the same issue as your other reports: the platform behavior does not work well at such tiny scales, because its built-in tolerances work on the scale of 1-2 pixels, which is a significant fraction of the size of the object.
In this case it probably falls down the hole and simultaneously tries to move right in to the wall. When it finds it can't move in to the wall, it moves backwards out of the wall, on a scale of pixels. It can't find anywhere until it moves all the way back to the left.