verinne

Using 06a, have same bug. Curiously, it's only affecting 1 out of 2 players on the server. The unaffected player is OP. Spawns player inside a solid hill. Upon hollowing out they appear midair and fall to their death.

Reproduced with Modded 1.7.10 (Using Et Futurum and MorePlayerModels so it's not clean or clear at all, but perhaps confirming the bug will help).

Bug left me in an odd state: could move, interact, etc
Did not take damage, fall damage, could not be seen nor targeted (Zombies ignored me, walked through players)
Arrows passed through me
Could still hit and kill other players.
Model was red and in death animation the whole time.

Maybe this is related to models not getting removed on disconnect?

Even if it's a technical block, isn't this the case if you have 50 extended pistons then?

If I had to guess I'd bet it would be the pistons checking which block they are attached to every frame.

I think a good solution would be to try for a radius of 16, then if it can't find a way do reverse pathing for the full radius from the player to zombies. that should take care of the situations with a player on a 2 block stack.