I just checked here and see the same thing. The error seems to reference a missing .rx2 file.
So the .prog files in the Grooves folder for Expansion Pack 2 must reference .rx2 files installed elsewhere on the system. I recall recently uninstalling Cakewalk Beatscape and deleted all .rx2 files from my Cakewalk content folder to recover disk space because I never used them.
So at least in my case I know why I am getting this error in Dim Pro.