Hey Grant,
There seems to be an issue in RPM v.6.67, when trying to save Element sets to a file, and loading it again on either the same or another pass.
The problem may be related to scenes created with previous versions of RPM, which is the case for most of our template files.
I've tried stripping RPM data, and recreating from the scene (which is still an "old" scene) - but the problem persists even after recreating new RPM data from current setup.
(MAX 2017 - Vray 3.60.03)
As you can imagine, this is quite inconvenient, when your only option is to manually recreate 10+ elements in 20 passes.
The data seems to save fine, but it can't load/shows uip empty/undefined.
See attached files for what I'm getting.