I'm going to take a guess that the "swig" package is not installed on your
system so when you ran the "cmake ../" step prior to building op25 it generated
makefiles without swig support. It'll still compile and install quite happily but
won't run... (ask me how I know!)
To fix the problem you need to do a "sudo apt install swig" or whatever is
equivalent on OSX, then delete and re-create the op25/build directory followed by the
remaining build/install steps.