First thing I would do is make sure you put the User frame data into the PR as cartesian.
$PR_CARTREP = 1
PR[210:Uframe5] = Uframe [5]
Then you can manipulate PR[210] X,Y, or Z all you want, And stuff it back into the userframe.
(And then switch cartrep back to Zero if it causes other issues).
Thanks! Hadn't considered using CartRep programatically. Basically I'm just doing some X,Y,Z adjustments to PR210 with 2D vision and a laser for z offset, but always relative to the origin of UFrame 5 hence why I was using it as a reference in the program. I'll try this and see if that fixes it.