Huge Chunks of World disappearing!

I have noticed the same thing tonight on my Apple iPhone 7S running is 11.0

Parts of the screen are not rendered when first logging in. I’m afraid if Zi fall
before it finishes rendering, I’ll be stuck
i’m papa land

I experience the same issues on my realm frequently. it doesn't seem to be related to any specific area or action or amount of people on the realm.

Also having this quite badly in the latest update.
Same on Xbox one, WIndows 10 and android versions accessing the same realm.

This is happening to us now on our Realm.  We just started a new realm on 2/17/2019 and exploring we saw a huge chunk missing.  I logged out standing by the missing chunk and was never able to log back in.  The game got stuck on "Building terrain".  I then decided to create a new world in the realm and this time, the chunks seemed to load around the spawn location with no problem.  After logging out and logging back in later that day, a huge chunk near the spawn was missing.

EDIT:  Right after posting this I wanted to see if I could see the issue locally by saving the world and running outside of Realm (locally).  I saved the world and loaded it and the chunks loaded properly.  When I went back into my realm the chunks appeared again.  It's like the save made the world regenerate everything, weird.

This is happening on our realm as well. Started a few days ago. 

Able to fix by closing realm for 5 minutes and reopening but it continues. Some chunks are repeat offenders.

I think this is somehow related to https://bugs.mojang.com/browse/MCPE-40538 . This started happening in my world at the same time as 40538. Whenever people entered the End, I would start losing chunks in our spawn town around 2-3 days later. This was fixed by downloading the world, resetting the End (meaining, I deleted all the End chunks with MCC tool chest), and re-uploading the world. I kept my members out of the End for a while and it didn't happen again... Until we had a new member start going into the End (unbeknownst to us) and we started losing chunks in town again. I then reset the End once again, made sure nobody entered, and it stopped happening.

40538 was said to be resolved (for newly created End portals) in the most recent update. I destroyed our existing End portals and created a new one for my members to use. For about a week, we were okay. We are now losing chunks again. I have found out I can reload the chunks by clicking the "close realm" button and then opening the realm again.

I'm not sure if this is directly caused by the same bug that is causing 40538, but there must be some kind of correlation, because this is NOT happening at all in my world when no End chunks exist.

One other thing to note is that this does not happen if the world is offline (which I guess is why closing and then reopening the realm resolves it). When I've had the issue and then downloaded my realm to reset the end, I logged on in single player mode and the chunks were just fine.

edit: I see that this report has been open since 2017, so this obviously can't have been CAUSED by 40538 specifically, but perhaps something that's causing 40538 might also be causing a resurgence in this issue as well.

edit: This is now causing chunks of our nether network to disappear almost every time anyone enters the nether (as described in REALMS-1569 , which is marked as resolved). I can reset my realm to "fix" this, but I'm at the point where I have to reset my realm every other hour to keep it running properly.

Thank you for your report!
We're continuing to track this issue at REALMS-1553, so we will resolve and link this ticket as a duplicate.

If you would like to add a vote and any extra information to the main ticket it would be appreciated.

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