After playing on a server (or bedrock realm) if you immediately load a local single player world you start afresh (no inventory/XP, at spawn, etc.)  However if you exit and reload you get the correct world/inventory/etc.

To reproduce:

1) load a server (or realm) and quit back to UI.

2) Navigate and select a local world to play

Expect Behaviour:

1) world loads normally, inventory and XP is correct

2) you return to location you last logged out of the world

Actual Behaviour:

1) On first load you are presented with a "new world" (no XP/inventory)

When i first encountered this i thought i had lost my local world progress.