block levitating

how to reproduce: (use commands)
1) /fill a large area 100x100 with 1 layer of glass
2) /fill the with repeaters 1 layer above the glass
3) /fill with air the layer of glass

what i expected: all the repeater would pop off

what happened: most of the repeaters didn't pop off

-this happens with repeaters, comparators, redstone dust, and all the type of rails