While exploring new areas of the map, the game works normally.
When making a return pass through an area that was just explored, the game "despawns" the world in certain sections! The smallest looks to be an exact square with maximum height from bedrock all the way up.
However, there have been other much larger chunk despawns that aren't perfect squares.
Provided here are 3 'screenshots' of two despawn points in the ocean directly next to each other:
(1) Eastern despawn with two maps (Zoom 3/4 and Zoom 0/4) hand-in-hand to see what it looks like on the map.
(2) Same eastern despawn, no items in hand to provide better view.
(3) View (facing south) of the two adjacent despawn chunks.
These photos were taken not on the return pass, but on a bonafide return trip in order to document the issue, or see if it was naturally resolved.
By despawn, I literally mean all blocks have been removed. Going into it you fall straight down to the bedrock and die.
This is a Survival world (Achievements enabled) on Normal mode with two-players playing local on same console, non-realm/server. Natural texture pack, save file is about 185MB. I'm always signed into the Xbox/Microsoft/Minecraft accounts on main menu before loading the world.
I will provide more photos and details of other locations upcoming, especially the worst one.
The ONLY blocks that don't despawn are source blocks for lava and water.
This despawning bug has left us terrified, especially without Jagex readding the Quit Without Saving feature, we have no control when our world is destroyed like this!
Attachments
Comments


With all due respect, this is NOT a duplicate AT ALL.
MCPE-19308 is truly two issues in the same bug report - it is about rendering issues - about the blocks taking a while to show up, and a little bit of this. I am aware of that, I have that issue too.
The sole focus of this bug is that the blocks were ALREADY rendered, and are now COMPLETELY destroyed by coding. Please reopen this, unless Mod Neko believes on behalf of Jagex that the two issues are resolved in the same strand of game coding, then I will concede.

Four screenshots added - one showing our 3x5 map at zoom level 3/4. We are standing right at the crosshairs (green indicator). The destroyed areas are at the western/northwest (black areas). Closeups show them are pure black after the areas are destroyed by the game coding.

Three more added of another in-person destroyed chunk where it's showing and you can see the snow thinks there's supposed to be land there, and it'll sit and form, but then within a couple of seconds it falls down to the abyss because there are no actual blocks after the coding destruction destroyed the area.

Reopened because it describes a different issue from MCPE-19308.

You've reported this for version 1.6.1, but version 1.7.0 for Switch was released two days before the date of this report. This suggests the possibility that an error occurred during upgrade, either of the world or of the game. Please try to provide some more information:
What version were you using when you created the world?
If you created it prior to 1.7.0, what version were you using the last time you opened it before the problem appeared?
Did the problem only appear when you opened it with 1.7.0, or was it already happening? If the latter, what was the first version you saw the problem in?
Does it affect any other worlds? If you don't have any other worlds or don't want to risk damaging them, can you reproduce it in a test world you create using 1.7.0?
BTW, the evidence from your description and your screenshots (particularly the one that shows snow layers floating over the hole) suggests that these chunks were already generated but that the block data in them is either missing or invalid. Either could happen as a result of an error during upgrade conversion. If it's merely invalid, it's possible that the information about what blocks they contain is still present and a fix could repair it, so you might want to avoid continuing to play this world until a fix is available; otherwise, you risk further damage that could destroy the information.
Also, something must have been different about these chunks that caused the upgrade to malfunction. It would most likely be related to what version generated those chunks initially, or last updated them. There's no real way you could be expected to know that, but if you know of anything unique to the damaged chunks, such as that they were all last updated in one particular session of play or that the game crashed when you were in or near them, that could be very helpful to us.
Thank you for your report!
Crashes such as these are logged automatically, and will be looked into further by the development team.
If you need help or support you might like to follow a link below.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki
Duplicate of MCPE-19308.