Mobs in general will not walk over short blocks (ones that are shorter than a full block, like daylight sensors). This issue has been fixed for some common blocks (like lower slabs) but not for most other blocks. This is best seen when there is only air below the short block.
Currently affected short blocks: Grind stones, beds, lecterns, stone cutters, chest, daylight sensors, end portal frame, ender chests, bells, unlit campfires, chains, conduits, and end rods.
And probably other short blocks that i forgot about
How to reproduce.
1. Go 30 blocks off the ground, and make a 1 wide by 10 long row of blocks
2. Spawn a zombie on one end, and a villager on the other end
3. Between the mobs place a couple of the above mentioned blocks in the floor
4. Neither mob will walk over the above mentioned blocks
5. Sometimes mobs can pathfind over the blocks, however, its not really.. reliable? they will often jump around, stagger, stop, or fall off the block. Best seen with the grind stone.
Expected result:
Mobs would walk over and pathfind across these blocks with little to no issue.
Full demonstration, and explanation of this bug coming soon
Not a duplicate of MCPE-47075, that report was only for slabs/soul sand/brewing stands/enchantment tables. This is a related post for all other short blocks
Linked issues
is duplicated by 3
relates to 2
Attachments
Comments 25
Relates to MCPE-98568.
@unknown: Your videos are too short to confirm what you say, and my longer duration test with virtually the exact same setup contradicts your conclusion. The drowned do seem to delay a few seconds while they stand on a short block, but before long they climb down and start wandering around. Once they're wandering, it can take a few more seconds for them to look in the direction of a villager, at which point they target them. I don't know why they don't target them while they're still standing on short blocks; maybe it has something to do with their eye level being above the villagers' eye level. But in any case, they behave as you would expect them to within a few seconds.
Also, you didn't explain how a drowned came to be attacking a villager in this latest video. It's as if you hoped we wouldn't notice.
These hopefully will help. And the drowned was due to testing and that I was near the seafront with mob spawning turned on. It was how I originally found out about the drowned issue being that a drowned walked on to a bell a got stuck on it.
Unfortunately, it looks like I haven't been testing in the version I thought I was. I was a tester for Microsoft Preview, which I still have installed. As you might know, Preview is the new way of delivering Beta releases. My Preview release was shown on the main menu as 1.18.10.23. I was confusing that with 1.18.20.23, the later version you listed as affected. I have now learned that the internal release number is 1.18.2.3, which seems to mean that my tests were done on an even older version than yours, which in turn should mean that your version should be after the fix, but the current circumstances are too special and unusual for me to be confident of any conclusion I might draw.
What I need is to test your world in the old-style Beta, the release you're using yourself, but I'm reluctant to install that given that I also have Preview installed (not to mention the problem people regularly have trying to uninstall the Beta releases). I'm going to look for another moderator who has the current Beta installed and ask for help. Check back later.
Moderator @unknown has tested this issue in 1.18.20.23 Beta and found that this issue is fixed for all mobs except drowned, axolotls, and turtles (apparently, aquatic mobs that can also walk on dry land). The changelog for 1.18.20.21 Beta didn't explicitly mention this bug report, but it did fix all other mobs' pathfinding, so I think the best way to handle this is to split Brent's report MCPE-152043 back out and submit it to Mojang as a separate issue.
Usually this only happens in a corner or between a block if the mob is on the taller block. They also do have an issue with being slowed when pathing but I covered that at (https://bugs.mojang.com/browse/MCPE-98568).