Chunks reset and missing in ticking area on Minecraft World

A world on my Minecraft Realm I have been playing on for a while now suddenly got rid of some saved chunks after leaving said Realm, which I figured out after joining again a few hours later. Those chunks seemed to be specifically located in a ticking area.

I know for certain that this bug did not occur because of the Realm updating to 1.14.0 while I joined, as I had been playing on the recently released 1.14.0 version for a couple of hours now.

Luckily I could restore a back-up automatically created by the realm. Hooray for that feature!

 

A screenshot from an earlier back-up of the world.

 

A screenshot of the same area, where chunks have been reset or are just straight up missing. This screenshot was taken from a back-up of the world which was made only 20 minutes after the back-up of the first screenshot.

 

Both world versions (the bugged and the backed-up one) can be found in the following folder on Google Drive: https://drive.google.com/drive/folders/16oqfhomml4opVs_rCtk2B0Dg0wiB6E2P?usp=sharing