CS3 software version 2.6
RailControl Pro is fully compatible with CS3 software version 2.6 Track Diagrams as of version 3.4.2. Read blogpost
CS3 software version 2.5
Märklin has added full compatibility for Control Desk style track diagrams with software version 2.5. Make sure RailControl Pro and the software on your CS3 are up-to-date to enjoy all your Track Diagrams. Read blogpost
CS3 software version 2.4
For unknown technical reasons, Control Desk-style diagrams don’t show up in the CS3 Web App and, consequently, are also missing in RailControl Pro. On the other hand, Panels are properly displayed in both applications.
Convert a Control Desk to a Panel
It is possible to convert a Control Desk to a Panel, as explained on page 35 of the Märklin CS3 User Manual. This way it's possible to show the articles in the Track Diagram on RailControl Pro.
Related blog post: The curious case of Märklin CS3 Track Diagrams