Hi Allen,
Hope you are well !
I think STOP in the rotor control may or may not work depending on rotor mfg and/or model unless yours worked before. Mine is a Hygain DCU-3 and STOP works as it should. Rotor OFFSETs are set in the Band Table so a quick check of that will show if for some reason an offset got entered. I'm sure you checked the usual stuff like drivers and the like, also disable/re-enable the rotor, also assume the rotor works as it should without LOGic. I believe there is still a free standalone rotor controller application called LP-Rotor that you could try if your running Windows, there might be others as well but at least that may help trying to figure out if the rotor controller itself is the culprit.
73 de Brad, N8GLS
PS: Also PSTRotatorAz is another standalone application one can try.