After updating to AA r147, the Atomic Reconstructor doesn't convert items that are on pressure plates anymore. It doesn't actually matter where the pressure plate is in terms of distance.
Steps to reproduce:
1)Place an atomic Reconstructor, set it on pulse mode and power it.
2)Place a wooden pressure plate in front of it.
3)Drop some canola seeds on the pressure plate.
4)The Reconstructor fires, but nothing happens.

If you remove the pressure plate and drop the canola seeds on the ground, they get converted.
I know it was different before because I had a setup that would automate the Reconstructor, that used a pressure plate, and I noticed it doesn't work anymore.