Good morning.
Pressing the crouch-button on any chest type with any trapdoor type over it, standing in the trapdoor and trying to move off the chest in any direction will make you fall off. This has been tested on multiplayer servers too.
Trying to crouch off a chest without a trapdoor over it makes it act like a block and wont make you fall off.
My theory is that the trapdoor is trying to push the player off the chest and because the chest has a smaller hitbox, it succeeds.
This bug can be re-created for testing by the images attached with this post.
Linked issues
testing discovered 1
Attachments
Comments 24
Also happens on the wide edge of anvils, but not on the narrow edge. So the bug probably happens for any edge that is not aligned to the block grid, not just chests.
Does not happen for glass blocks, which is transparent, so the transparency of the chest has nothing to do with it.
Testing discovered MC-147266
If you're supposed to be pushed into "swimming" mode by a closing trapdoor, albeit either crawling or swimming, either way, this bug would then not be reproducible anymore.
Resolved as "Cannot Reproduce", as it is no longer possible to stand inside of a trapdoor as of 1.14.
This is actually incorrect for your lower half (I understand crawling is activated with a trapdoor in your head half). In 19w39a (which I assume is carried over from 1.14.4), place a trapdoor on the lower segment of a block, with a solid block underneath. Open the trapdoor so it faces up. Stand in the trapdoor's place. Close the trapdoor. The player does not clip upward above the trapdoor. Walk out of the block: you notice you do not fall the short distance.
You were standing inside of a trapdoor.
as https://twitter.com/henrikkniberg/status/1113084315615793152 explains, the reason for this I suppose is that these crawl checks only occur on the head half, not the feet half. Regardless, the whole process comes across as very hacky and I don't know if Mojang would prefer all these mechanics to remain static forever.
On further investigation, making your feet to stand inside a trapdoor (as described above) prevents another trapdoor above it from triggering crawling. Thus you can be standing inside 2 trapdoors at the same time. Again, just trying to point out that these crawl mechanics are simply not fully grown. Helpful, yes, but not really something to leave alone.
Please do not mark unreleased versions as affected.
You don't have access to them yet.