My friend encounters problems playing in my world

My problem is occurring in multiplayer mode, in my world, when I play with my friend. It turns out that when he leaves and comes back, he loses all his items and is not born in the same place where he left / left, but in the spawn location (where you appear after creating the world). The "keep items in inventory" option has already been activated, but no significant changes have been made. This issue occurs in V1.16.221.01