Some issue is causing the Mux block output not to display on a real-time scope.
When you connect Mux block output to a real-time Scope block, sometimes you cannot view the output from the Mux block. This issue occurs because the Mux block produces a virtual signal. The code optimizer removes the virtual signal during the build process for the real-time executable.
Insert a Gain block with the Gain parameter set to
1.0 at the input to the real-time Scope