Mobs in general will not walk over short blocks(ones that are shorter than a full blocks, like slabs). This is a pretty easy thing to spot in survival, as lower slabs are used everywhere, so you will typically see mobs stuck on them, not walking over them, or jumping in circles on them.
This does not apply to all blocks that do not have a full hitbox, just a few.
Ones i have tested are: Lower slabs, Enchantment tables, Soul Sand, Brewing stands
This should also affect farmland and path blocks, but those have incorrect(full sized) hitboxes, so are fine in this case.
Keep in mind, mobs not walking over these blocks, is only an issue if the block has nothing below it.
How to reproduce.
1. Go 30 blocks off the ground, and make a 1 wide by 10 long row of lower slabs.
2. spawn a zombie on one end, and a villager a couple blocks away.
3. You will see that neither the zombie, nor the villager will walk away from one another.
4. Start placing full blocks under the lower slabs, and they will start to move again. This can be repeated will all blocks listed above.
Expected result:
Mobs would walk over and pathfind across these blocks with little to no issue.
Below you can see one of my set ups for testing this. Placing solid blocks below any of the short ones, allow the mobs to move.
Full demonstration, and explanation of this bug here:
https://youtu.be/qR5M5v0XDM0?t=172
Linked issues
is duplicated by 21
MCPE-48122
Mobs can't find a path on half slabs
Resolved
MCPE-51318
path finding
Resolved
MCPE-53729
ALL mobs can't path on half-slabs, and just spin in circles! (Xbox One&Windows 10)
Resolved
MCPE-55421
Mobs Continuously Jump When On Non-Full Blocks
Resolved
MCPE-57128
Mobs Can't Pathfind Over Floating Slabs Or Beds
Resolved
relates to 2
Attachments
Comments 21
I can verify this affects 1.11.0 at least, and in my case this happened in survival with an enderman freaking out on soul sand.
I have had this happen. I had used "bottom" slabs as a 2nd floor and wondered why my villagers were not moving, changed for top slabs and they were fine
noob1884: This issue is fixed in 1.16.100.52. The knock-on effect is a new issue that needs its own report, even if it might possibly have been caused by this fix (which is something we wouldn't know; the developers will have to figure out if that's the case).
This bug still affects grind stones, beds, lecterns, stone cutters, chest, daylight sensors, end portal frame, ender chests, bells, unlit campfires. chains, conduits, and end rods. So, every short block not listed in the report 😅 reopen, or new report?
Since the developers have already finished their work order, their ticket for this will be closed. I'm not sure it can be opened again. and in any case it wouldn't be standard procedure for either them or us, so we'd really appreciate it if you could make a new report. Thank you for asking!
Fair enough, will make a new one. Likely just a copy/paste of this report with updated information about whats currently in the game🙂
New report. demo of the other issues coming soon MCPE-100622
Can confirm to affect 1.12.0.9 Beta. Seems as though they cannot correctly path-find over any block that does not have a (1X1m) collision box (With a few exceptions like top of slabs, thanks to Silent for clearing that up).