A couple more pieces of information from the APCC and NINA logs.  NINA was reporting all night the meridian flip was to occur are 22:37.  The APCC logs show the meridian limits were reached at 22:34:52 and the mount stopped.  I manually flipped the mount at 22:35.  The NINA log shows that the meridian flip didn't occur as scheduled because the mount was already reporting on the east side - because I'd flipped it manually.

I'm curious why NINA isn't reading the limits file that I've indexed in the Smart Meridian Flip plugin?