Starting with 0.12.3555 any new save game will fail to load and instead starts a new playthrough.  See this video for example.  I can load any old save created before 0.12.3555 and those load correctly, but then any save i make afterwards can't be loaded.  Any new save using 0.12.3555 fails to load.

Windows 11, xbox gamepass version

 

 

 

I fixed the issue, so maybe this will help someone else.   Long story short, i bought the game from steam and imported my xbox save game.   I have no idea why this issue began with 0.12.3555 and persisted into 0.12.3562 only for the xbox game pass version.

 

Process: I exported a working save game from xbox game pass version of grounded, it put the export at: "C:\Users\%username%\Saved Games\Grounded Windows 10 Exported".  Then i bought the game on steam, joined the beta, started a new game, saved and quit.  That created a new save game location at: C:\Users\%username%\Saved Games\Grounded.  I copied the xbox game pass exported game directory from "C:\Users\%username%\Saved Games\Grounded Windows 10 Exported" into C:\Users\%username%\Saved Games\Grounded.  I restarted the steam version of the game and was able to load my saved game from the xbox game pass version with no issues.  I have played for more than an hour and saving/loading works correctly.

More info:

The problem appears to be related to how the gamepass version saves games and syncs those saves with its cloud service.  I was able to get the game to sometimes load correctly in xbox game pass by manually deleting save gave directories.  On my PC, those folders/files were located at: C:\Users\%username%\AppData\Local\Packages\Microsoft.Maine_8wekyb3d8bbwe\SystemAppData\wgs\0009000005263373_0000000000000000000000007D7CFB3C.  Before i started there were about 2300 directories there and the game reported about 1100 saves.  I deleted any directories older than 10 days, then i was able to load a game, play for awhile, save the game and the saved game would load correctly.  The game reported about 80 save games after the folder deletions.  However, the solution didn't last.  After 30 minutes to an hour of playing, i wouldn't be able to save and load the game anymore, i.e. the original problem described in this thread returned.  I could go back to a save game that worked 30 minutes ago, but any new save would fail to load and instead start a new playthrough.  I also couldn't export those save games, it would say the game exported, but the path was blank and it didn't create a new directory/files.  Frustrated, I figured I could avoid the entire xbox gamepass cloud sync system by buying the game from steam and importing my save.  That worked, see above for the process.  Bummer i had to pay $30 for a game I was already getting via my gamepass subscription, but it worked, so worth it to me.