I have a piston elevator in the Nether (on the Nether roof).  As it ascends, the elevator deck sometimes glitches - the blocks do not all update in the same order.  As a result, the player sometimes glitches into the deck of the elevator (getting legs stuck in solid blocks).  Glitch is intermittent (happens on about 50% of elevator rides) and only occurs if the elevator ride lasts long enough (at least 50+ blocks, although the glitch rate appears to go up the taller the elevator).  I have captures to show the issue, but they are too large for this bug tracker.

If reproducible, to reproduce:

1) create a simply piston elevator at least 100 blocks tall

2) stand on the deck of the elevator and activate

3) if the glitch does not occur, ride the elevator back to the first floor and repeat steps 2 & 3