Every time other player enters my world it gets rid of their xp and their items

2 things. One... I go to near the ocean with my diamond armored horse... step off and horse disappears.. the only thing I can see is bubbles.. no sounds of the horse dying or anything 😓. 2 every time a friend enters a world of mine (that has been there before) it puts their xp back to zero and they have no items on them that they left with.