I've got the same issue, so perhaps I can clarify.
Sometimes after saving an RRD, it cannot be opened again. If you attempt to open that newly saved RRD, nothing happens. If you have a working RRD open, and attempt to open a broken one, the working RRD stays open as though you did nothing.
This doesn't happen with every report, but certain ones consistently trigger this bug. I'm still testing to find out what that trigger may be.
So wstewart's post clarified:
I created several RRD's in solution builder, ran and them saved. When I open Logicity solution builder, select the RRD it does not appear in the display area (Display Name | File Name). I can recreate it and the same thing happens.