If a player passes through a Nether Portal while in sneak mode, that player retains some properties of sneaking after coming out on the other side.
Cannot open chests, flip levers, etc.
Visually appears crouched to other players (including nameplate being hidden by opaque blocks)
Moves at full normal speed, despite appearing crouched
Falls off of block ledges, despite appearing crouched
Able to break and place blocks normally
Effect remains until player presses/releases sneak key.
Tested on a Realms Survival world in 1.8.3.
Updated wording used, and discovered that I am duplicating MC-10657, which still persists in 1.8.3. This issue should be closed and marked as duplicating aforementioned issue.