For Melodica-Me in particular, but also for general consumption:
Lowboy and I have been speculating about the Solist. Do you think it is possible that this was a prototype model that predates the Professional and that was circulated to a limited number of professionals for evaluation? I have been unable to find any evidence that there was ever a meaningful production run on it. How you acquired yours might tell us something, for example if you got it from someone who might have received it for review. A name change on the version to be marketed from “Solist” to “Professional” would make sense. The Solist has to fit someplace in the line of development that led up to the Piano 36, unless it was just a version produced for some particular musician(s).