If you place a row of vertical pistons (bottom and top) that have blocks in between, and then tile it, one of the columns must be missing a block for it to work. The column design is like below and then tiled:

Down Piston (d)
Block (x )
Block (x )
Block (x )
Up Piston (u)

So when tiled, the setup looks like:
(o = missing block)

Doesn't work:
ddddd...
xxxxx...
xxxxx...
xxxxx...
uuuuu...

Works:
ddddd...
xxxxx...
xxxxx...
xxoxx...
uuuuu...

Attached is a world with the bug displayed. It is set up to test;
-all 4 orientations
-different multiples of tiled columns
-different blocks missing

Update:
-I have tried various methods of powering the pistons and the ladder up to the upper row. It doesn't make any difference.
-The block being moved also does not matter (tried wood, cobble, dirt, stone, wool, glass)