Since some 2.1 preview version, can't remember exactly which, sheets that are supposed to slide in from the bottom fly off the screen on Chrome, iOS and Android.
This has something to do with the show animation, turning it off fixes it.
I wasn't able to reproduce this in the kitchensink nor isolate it yet. In the isolated test I did the other day it worked.
Still thought I file a bug, maybe somebody else can provide more info. :)