I managed to get this shader working wonderfully in Maya 8.5 for use in AE with RSMB. All went off without a hitch. But now...
A different test shot isn't working. An Fcheck playback shows only a series of greenish-yellow frames, identical, one and all. A former, successful attempt translated my camera move into all the colours of the rainbow.
Now, my busiest frame is read as having a "max displace" of 0 pixels. That's "zero". It's as if the camera was locked down. I assure the reader it isn't.
lm2dmv_v.2 shader on everything (it's a panning shot)
Motion blur set to full.
Shutter Open: 0.5
Shutter Close: 0.5
"Pass Custom Alpha Channel" checked