I should be clear this bug has occurred on more than just Windows 10 as it has also affected my Xbox One console.

So I recently bought copies of Minecraft Windows 10 for my SO and a friend of ours so that we can all play together with other friends. A max of 4 people together on a base world. (not a realm)
Well previously before we downsized to a single Xbox one console a world of ours disappeared from there. Just one day there, one day gone. Poof, nothing. No help for recovering lost worlds on Xbox one. So we suffer, choose not to play for awhile, and move on.

Since then I got Win10 for him and last night during a trip to the nether he (the host of the server) died and we all decided it was enough at the time since it was late anyways. We save and quit. (but he did not choose to respawn yet)
Today we decide to count our losses and move on, we boot up the game and the world is gone.
Not this again.
We tried any information we could find to try to restore the world, but nothing has worked.
We had 2 worlds (and an old realm) and when we look in the folder we see two worlds, but one has a blank .txt file and the other has a .txt file with the name of the world inside of it.
(we tried to make a copy and rename the txt file, but nothing changed as well as making a new world and copying the .dat files of the blank world to the new folder, still no change)

Honestly this has happened twice now on two versions of the game, even though they're both Bedrock Edition.
I got all these copies to play with friends, but we're not having much fun when the threat of losing everything is constant.
We already suffered before thanks to the instant-kill Blaze bug and now we've lost two worlds we've worked very hard on.