You are correct it’s not a button. My bad, since the white bar never moved I assumed it was binding to a button and not an axis.
I tried re-mapping the rudder and finally got it to work where the white axis line would move. However when I went back to the sim, moving the rudder would do nothing as rudder was frozen.
This problem was a PMDG 737 specific problem, as I was playing with the FMC and maintenance functions and it finally worked correctly. When I get some free time I will try it again to see if it keeps working. Thanks much appreciated with the help.