My girlfriend has that same issue too. We where on a server hosted by me, and we all disconnected inside of a cabin together. Me and my other 2 friends rejoined just fine, but my girlfriend was not sitting on the floor where she was. When she joined she had to make a new character and spawned on a different island. We looked for her stuff but found nothing, not even a gravestone. We even dug all around the cabin and looked on top of it. On the other island away from us. My girlfriend died from a bear and made a new character. However this time she did not spawn, commands did nothing, she was just frozen there. She went as far as restarting her PC but every time she rejoined it just showed her stuff on the ground and when making a new character would just freeze.