Converted world will not load properly in 1.9 and 1.10 - Bedrock Realms

The latest update to Minecraft (version 1.9.0) has broken my Bedrock Realms server. The server will load a selected area around where I last saved in version 1.8.1, but this area is surrounded by glitchy void space. Attempting to exit and re-enter the world results in endless "Building terrain..." loading screens. Restoring from a backup yields the same results no matter how far back I go. The oldest automatic backup is from November 2018.

 

This is an older world that has been converted from an Xbox 360 file to an Xbox One Edition file to a Bedrock file.

 

I can download the world from the Realms server, but attempting to open it crashes the game entirely regardless of platform (attempted on: Nintendo Switch, Xbox One X, Windows 10 PC, Android). This world had absolutely no issues in 1.8.1. I have attached a screenshot of part of the void effect as seen from the Android version, 1.9.0.