When you generated your dynamic model with make_dynamic_model.sh, you have also generated a source file that ends with "_dyn.cc". If you open that file, towards the file end there should be a variable named "__name", for example:
char __name = "mod_TT2";
This is the name that the dynamic model is identified by inside of openCARP. Please make sure that the value of __name matches the model name that you are using in the openCARP parameters.
For example, dynamic loading does not work if for example the .so file is renamed after generation.