I'll briefly explain the images, because they tell the story better. The 01 image is the setup, two cases. One with a wall with the height of two blocks, the second case (the one with a lapis block) with a height of three blocks. I have only put that ONE lapis block, to signify which block is the "troublemaker".
In the case of the 02 image, pressing against the wall, walking up the stairs nothing weird is happening, you walk unhindered up the stair.
In the case of the 03 image, pressing against the wall, the block positioned as the lapis block is most likely being calculated as an obstruction for your head going up, so you stop dead and can't move past unless you start looking more to the right - at a certain angle you will move up the stairs.
Walking up a spiralcase of stairs and you keep to the outer wall of it, you'll end up stuttering and getting a bit stuck.
Related issues
Attachments
Comments
migrated
migrated
Dupe of MC-61245
migrated
I'll re-test once the hitbox is fixed to make sure this isn't a separate and newly introduced problem with diagonal hitbox obstruction. I agree that it could be a duplicate, but I don't see how the height of the stair hitbox should make you hit the lapisblock in the pictures. If it was above the stairs, fine, but "inside a wall"?
migrated
Re-open this issue!
This is not a dupe of MC-61245 which pertains to the hitbox of placing stair blocks but that is not the collision issue which is happening here, which is caused by "catching" on what should be completely flat walls - another way you can test this is by using half-slab stairs which have the same issue, if you walk into them at a 45deg angle you will "catch" on the wall and it will block your movement - this is not the same behaviour as in previous versions of the game and is not the same issue as MC-61245.
kumasasa
Relinked to MC-65230