Minecraft UWP save failure on Windows 11 Insider due to sandbox regression

I am experiencing an issue where Minecraft for Windows (Bedrock) does not save data correctly on Windows 11 Insider builds (Canary, Dev, and Beta). After extensive troubleshooting, the problem appears to be caused by a UWP sandbox initialization regression in these Insider channels.

Summary of the issue:

• Minecraft creates a fallback folder at: C:\Users\<user>\AppData\Roaming\Minecraft Bedrock This folder should never exist for the UWP version of Minecraft.
• The correct UWP save locations remain unused: LocalState SystemAppData\wgs SystemAppData\Helium
• The Helium folder stays empty and the wgs folder is never created.
• Marketplace and cloud save features fail or behave inconsistently.

What has been ruled out:

• File system permissions (ACLs verified and correct)
• Incorrect launcher (Start Menu points to the correct UWP AppX entry)
• Corrupted Minecraft installation (package re-registered successfully)
• Microsoft Store or Gaming Services issues
• User profile corruption
• Missing or incorrect folder structure
• AppX registration issues
• System file corruption (DISM and SFC clean)
• Reinstalling Minecraft or Gaming Services
• Reinstalling Windows using Insider ISOs (Dev, Beta, Canary)

Key findings:

• The Minecraft UWP package installs correctly.
• The launcher is correct.
• All ACLs are correct.
• AppX re-registration succeeds.
• Despite this, the UWP sandbox never initializes, so Minecraft cannot access its restricted storage.
• As a result, Windows forces Minecraft into a Win32-style fallback mode, creating the Roaming folder.

Microsoft Support Response:

Microsoft Support confirmed that this behavior matches a known limitation or regression affecting UWP sandbox initialization on Windows 11 Insider builds (Canary, Dev, and Beta). They stated that there is currently no supported workaround on affected builds and recommended either filing a report here or installing the Windows 11 Stable build.

Conclusion:

This appears to be a UWP runtime regression in current Windows 11 Insider builds that prevents Minecraft (and potentially other UWP apps) from initializing their sandbox correctly. The issue persists across clean installs and multiple Insider channels. A fix would require changes to the UWP/AppModel runtime in Insider builds.

(I am about to reset my entire PC for a 3rd time, this time with the Windows 11 Stable build. Fingers crossed it fixes this issue.)