LAN World thinks returning Player is a brand new player (Happening since 8/26/24)

First of all, we're always connected to the Internet and our systems are nominal.

Issue Beginning:

Issue began with v1.21.22 on August 26 '24

A frequent player on my Bedrock worlds, whose gamertag is "Locomotivated" is now being treated as a New Player in multiple worlds.

Edit 010/4/24: We have ruled out most root causes, and it has to be an issue present on our local network and/or workstation(s), and/or some problem in how we are communicating with XBL / Microsoft / Mojang servers.

• We open a World, where this player has joined previously, but they cannot join with their current inventory and experience. They begin at the spawn point. This is true for all pre-1.21.22 worlds.

Further Details:

• This problem is true for all pre-1.21.22 worlds where the player has joined before 08/25/24 (basically anytime in the past).

• We rolled back 2 years, and it was true for those old worlds as well.

• We checked what Locomotivated did on their computer or account, or profile, and no changes were made that should affect Minecraft functionality.

So we believe this was triggered by the update 1.21.22, because it started date 8/26/24.

Player's Mojang ID is:

"{     "id": "2fb607a3d8ee45c6aa912d136e7d0524",     "name": "Locomotivated" }"

When this issue started, the player's Xbox Live Gamertag profile picture, which was unchanged for 4+ years, disappeared and is blank. Microsoft Support acknowledged this and there are screenshots of it on the Microsoft ticket below.

Stuff We Tried:

• We both uninstalled and re-installed the Minecraft Launcher as well as Minecraft.
  No improvement. The world still thinks Locomotivated is a new player.

• The player has Minecraft open and logged into, logged into the Microsoft Store and Minecraft Launcher and we've Reset the apps, and a few other minor cleanup tasks. Still no change.

• We opened Amulet. Amulet shows that Locomotivated's NBT data is still there, kinda frozen in time, complete with Inventory and Attributes, etc. Edit 10/4/24: Now we know that this data is accessible because the player can once-again play 'as themselves' when we host the World on Realms instead of local LAN.

We haven't been able to fix the World join issue yet. We opened ticket "6807570 - Progress and Saved Games" with Lance V. on Minecraft Help, and also on Microsoft:
Xbox account change resulted in loss of Profile Pic and serious - Microsoft Community