Minecraft worlds from Xbox One not syncing properly to Xbox Series X

I followed the steps and the world still seems to be de-synced/corrupted. I loaded, a saved and quit the world on the Xbox one, and powercycled, then loaded the world on the Series X, but the same message popped up. It did bring up a screen saying “syncing data for Minecraft” with a load bar, though. Any other ways to upload this world? *Apologies for the bad image quality*

Also, it might be worth noting that the world is labeled as being 456 MB on the Xbox series X, while only 350-ish on the Xbox One.

You can sync worlds from Minecraft: Xbox One Edition to Minecraft for Xbox One (bedrock edition) in game,
but you cannot sync the content across, as far as I know.

Hey there!

Minecraft's Cloud Saving will only sync your character and profile, worlds are stored only on the device you played.

If she really needs her old world back, you can use the Minecraft Realms trial to "download" the world on Xbox Series X, you can follow this Guide here.

When you play the new Minecraft on your Xbox One console, you’ll will be able to sync your existing worlds from the Xbox One Edition. Additionally, if you have a Realms subscription then your realms will
also appear on your Windows 10, iOS, Android, Kindle, or Gear VR devices (if you own them).

To sync your worlds from the Xbox One Edition to Minecraft:

1. Sign into your console with the account that you previously saved your Xbox One Edition world with.
2. Launch Minecraft and select Play from the main menu.
3. On the Worlds tab, select Sync Old Worlds if your existing games haven’t already been migrated.
   
4. Select the world that you want to migrate and wait for conversion to complete.
5. Your world will now sync to the new Minecraft when you sign in.

In addition to world sync, certain skin pack, texture pack, and mash-up pack purchases that you made on the console will also be available when you play the new Minecraft, and on your other devices.

When you play the new Minecraft on your Xbox One console, you’ll will be able to sync your existing worlds from the Xbox One Edition. Additionally, if you have a Realms subscription then your realms will
also appear on your Windows 10, iOS, Android, Kindle, or Gear VR devices (if you own them).

To sync your worlds from the Xbox One Edition to Minecraft:

1. Sign into your console with the account that you previously saved your Xbox One Edition world with.
2. Launch Minecraft and select Play from the main menu.
3. On the Worlds tab, select Sync Old Worlds if your existing games haven’t already been migrated.
   
4. Select the world that you want to migrate and wait for conversion to complete.
5. Your world will now sync to the new Minecraft when you sign in.

In addition to world sync, certain skin pack, texture pack, and mash-up pack purchases that you made on the console will also be available when you play the new Minecraft, and on your other devices.