Inventory and XP gone for 2nd player in split screen

After the "bug fix" of 1.16.210 I can no longer play minecraft with my wife. When she logs in as 2nd player split screen her inventory is gone and she is reset to the spawn point. This is very stressful because it means my wife has lost all of her netherite armor and items, her elytra, shulker boxes, and much more... Please fix this and actually test before you release