I created a staircase with a roof of upside down stairs above it. The top stairs were positioned such that if the player were to stand inside the staircase, they would fit, but couldn't enter the staircase under normal circumstances. If, however, the player moves in just the right way, they can make it partway up the staircase, but will then be stuck (keep in mind that the player initially wasn't able to enter the staircase). Furthermore, sprinting up the stairs causes the player to be able to make it to the top and exit completely, but unable to go back down the stairs, even while attempting to sprint.

I suspect this has to do with MCPE-30039, as the data presented from the report indicates that the coordinates are being rounded DOWN, allowing the player to run up the stairs without hitting their head on the upside down stairs above them. This hypothesis also explains why attempting to go down the stairs doesn't work, as rounding down in this case results in the player's feet clipping through the floor (since the player's coordinates are measured from the lower half of the player model on Minecraft Bedrock).

Steps to Reproduce

1. build a staircase using stair blocks (note: might be directional)
2. build a roof above the staircase, again using stairs, but upside down this time) such that there is a 2 block gap between stairs that occupy the same x and z coords.
3. sprint up the stairs
4. attempt to sprint back down

Expected results: the stair tunnel would not be traversible, as the players hitbox is 0.6 blocks in width, causing the upside down stair that is located 2 blocks above and one block in front of the stair you are attempting to climb to block your movement.

Observed results: you can sprint up the stairs just fine, but you cannot go back down.