With the comment above This issue seems to occur when world size surpasses the 700-750 Range
The Fact That Mojang really doesn't care either annoys me so much.
Your best bet is to stop expanding past 2k,2k anything expanding outside of that on all 3 dimensions at some point will kill your world
The only thing bedrock devs care about is pushing the market place to bathe in their endless riches
The fact it has been a year solidifies the fact no one is looking at it. They have everyone on the marketplace finding new ways to milk the money out of people willing to buy Minecoins