the simplest way i've found to reproduce this bug is
let the first block fall in the far left column (you can force it down by pressing down)
position the second block in the far right column as it's falling (do not press down)
once it's falling into the lowest row (again, do not press down), as it's falling naturally, press left once and it will slide all the way to the left where it's touching block 1. you can even wait until it's fully fallen into the last row but not locked into place and it will slide
i cannot get block 1 to do the slide, nor can i get block 2 to do the slide if i try to slide it from left to right (from the second column) so i think it relies on there being a block to bump into.
the simplest way i've found to reproduce this bug is
i cannot get block 1 to do the slide, nor can i get block 2 to do the slide if i try to slide it from left to right (from the second column) so i think it relies on there being a block to bump into.