Mux and Demux issues in 2018b (.slx file) Matlab version while running a 2009b (.mdl file)

After saving a .mdl file of the 2009b version in my 2018b matlab version, several attempts to run it usually returns the simulink file with labels along the mux and demux signal lines such as; double, boolean, ???, along each signal.

This output has persisted even after replacing the original mux and demux with the one in 2018b version.

How do I run this 2009b version in the 2018b version?

Thank you.