My issue is strangely the exact opposite of Mach's I attached a video of it happening.
World was to large to attach
@Mach
For clarity, this happens exclusively when going from the Overworld to the Nether. I cleared a spot in the the Nether where I show up after a crash, but most instances when I die it seems (based on sound effects) that I am being killed by skeletons and ghast.
I have had this several times, in recent weeks. Occasionally getting stuck on the building terrain screen and clearing being killed in the nether. If I die the game respawns at my bed and all my gear is lost. 1 in 5 in appear correctly in the nether. 3 in 5 I crash out and am at the wrong coordinates after reloading the game. The rest of the time I die in the process.
in reference to drwise's comment the problem does seem to go away if I lower render distance to below 25 chunks.....