Respawn and items disappear, reset randomly when logged in.

Respawn location  and inventory items randomly disappearing and reset on 

my flat world. 
this happens randomly, I only have a map in the inventory. But it doesn’t happen all the time , it saves all the builds I do but the only thing that it doesn’t save at times is my spawn location and the items I have on me. It’s like when I log on the spawn and items are in there, but the next time it doesn’t. So it’s not saving fully. I did have and email from minecraft saying about my data my have been leaked or something  that was the time I notice this problem on my flat world. Now I have checked to see if it does it on other maps and it does only the ones I’ve done before the email. It doesn’t do it on normal worlds. It seems to do it on flat worlds.