Step 1: left click with an encoded pattern on the crafting grid - it puts an 'image' of the pattern;
2: move cursor with the pattern on the 'craft result' slot, left click - it 'puts' the pattern (not an image, like everything else) there, but you can't take it back.

It doesn't allow to put pattern on the 'craft result' slot, if I haven't put an image of the same pattern on the crafting grid first.
'Result pattern' says 'Invalid Pattern'.

Minecraft 1.7.10
Applied Energistics rv2 stable 10
AE2Stuff 0.4.0.38

Closed: doesn't occur with the latest build.