Splitscreen player 2 inventory reset

I join my survival world and everything loads fine, but when player 2 joins, their inventory had no items or xp and nothing in their ender chest. Now whenever player 2 joins, its like he's on a seperate account as it now saves new items and quit locations but not the ones he used to have. We're not using a guest account and this used to happen a while ago occasionally but a simple restart would fix it. But as of the version running on the 5/4/2021 (and the weeks before) this hasnt worked and player 2 is stuck without any of their inventory in our 3 year old world. Any help or fix is greatly appreciated.