(@TimAhrens, I sent an email about this but never heard back, so I’m posting it here)
I have found a bug in RMX scaler. It does not work with glyphs that have a period in the name. For example, with .smcp glyphs RMX replaces the outlines with the outlines of the non-small cap versions—a.smcp gets the outlines of A, etc. It also ignores the width value I set and uses random new values. And sometimes the outlines are deleted if I have more than five glyphs selected.
This does not occur if I remove the period from the name, for example, .smcp to SMCP or _part. to PART.