The UI is loading slower than char load. Its creating a pitfall for the char. It forces the char to load randomly in the map. 5 times I have fallen to my death, appeared in lava, or just showed up in a cave.
If you can suspend char movements until UI loads that will give it time to correctly define the surroundings.
Thanks for looking into it Christopher G. Brown
Is this still an issue in the current Minecraft Snapshot 15w46a or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.