Having the same problem. Happens randomly, so I never know when I will start where I left off and when I will be in the sky over my original spawn point and fall to my death.
I am having the same issue. I randomly start in the sky over the original spawn point, fall and die even though I slept and reset my spawn point before closing the game. I have created a slime block platform over the original spawn point to try and help to keep me from dying, but sometimes I am a little bit off from the previous point (and I die from fall damage).
I am having the same issue. Also if I use anything else in my hot bar the milk disappears.