When Playing Multiplayer Guest Looses Inventory Upon Leaving

Put the summary of the bug you're having here
When Playing Multiplayer Guest Looses Inventory Upon Leaving
What I expected to happen was...:
Describe what you thought should happen here
I think that ALL players inventory should be saved, not deleted
What actually happened was...:
Describe what happened here
I was playing multiplayer with my sister between my kindle fire and her phone, and when she left, after playing for 2 hours, she had some diamonds in her inventory and when she joined again, her inventory was gone.
Steps to Reproduce:
1. Host a multiplayer world
2. Make someone join your world
3. Make them leave with stuff in their inventory
4. When returning the game, their inventory will be gone...