[Experimental] Massive chunk loading error from Y= -2 to -64 in new world

Is it a new one or previously created World? Could you attach the World or add seed?
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it's a newly generated world for the beta.

here's the seed:

253334972

Present in 4 newly generated worlds, playing in survival. 

So I did some testing and I can safely rule out all of the other experimental toggles except for the Caves and Cliff's toggle. Every time this toggle is activated, this happens, regardless of what other experimental toggles you have active alongside it. This is also true for that teleportation glitch that others have been reporting as well (which, notably, only happens when the player is below ground). Also, I noticed that this glitch does not affect chunks that are newly generated, rather it only affects (some) chunks that have been reloaded. I spawned into a creative world, dug straight down to the bottom of the world through the bedrock layer to see the chunks from below. There were no chunks that failed to load. I then went 200 in one direction, no errors. I then doubled back on myself for 200 blocks and that's when the chunks started failing to load properly.

After doing some thinking and looking at the issues related to this one, I am starting to become drawn to one conclusion: somehow, I think that the game thinks that there are two bottom edges or layers to a world: the y=-64 layer AND the y=0 layer, which was the designated end layer up until one of the early updates for the Caves and Cliffs changed that to y=-64. Think about it: on old worlds opened in this beta, all of the chunks that were previously generated got shifted up by exactly 64 blocks so that their bottom layer is at y=0 and for newly generated chunks and worlds, part of them are failing to generate past a certain point At which point does that happen? Directly after y=0. Somehow the game is back to thinking that y=0 is the bottom of the world, while still maintaining some notion that y=-64 is the bottom. This is an anomaly that the game cannot understand as there can't be TWO layers that are both considered to be the bottom of the world and so the game gets confused and starts going all haywire. That is what I think is happening.

Agreed.  If you open up enough area, you can see that some chunks do generate to the bottom of the world (presumably these are the ones with notable pregenerated structures in).  All else is void.

Out of curiosity I walked into the pit to see what would happen.  The message I got was "'player' fell out of the world"  

I'm afraid this sort of pre-alpha stuff is too much for me, seeing as I play for enjoyment and don't have unlimited time.  I'm opting out of the beta for at least this week.

Now wait a second, hold up! You don't need to fully opt out of the beta to avoid these problems, you just need to make a world without the Caves and Cliff's experimental toggled on. Everything else is OK.

Oh! And one last thing that I forgot to mention and this is important to note: when no experimental toggles are selected, the world generates normally down to y=0. Could this have somehow crossed over into the Caves and Cliffs toggle? I'm not certain, but maybe...

Not all near spawn found this about 500 blocks 1 way.

Its been happening on my android phone as well. Every time I reload the world it changes the chunks it decides to randomly delete. I went down a cave and nearly fell off, due to the void glitch. I then left my world and re-opened it while I was near the chunk error, standing close to the edge. When I re-joined, it teleported me to the surface and when I went back below the surface the chunk I was standing in had now also been deleted. I tried interacting with the area in creative mode and you can actually place blocks in the area, it works like any empty space should, you can bridge over the error to other chunks.

more specific, chunks that fail to load are from y=-1 to y=-64

Fixed on 1.17.30.34

this should be reopened, just had it happen on pc in 1.17.40.23
seed: 1846244985
created in 1.17.32
opened in 1.17.40.23 using caves experiment. closed minecraft then reopened the world