Three of us did the route yesterday. None of our Garmin's properly navigated the route -- although it recorded the route properly. (Fortunately we all knew the route forward and backwards, literally.) Given that all our Garmin's flaked, I wondered if the problems may be due to something related to Mount Weather.
Undermining that theory is the fact that my Garmin was willing to provide info in real time -- so I always knew when I was on the 12-14 percent grades!
BTW - If you haven't done the route in a while ( 56 miles, 4400+ elevation), it has gotten a bit less fun. The shoulder on 17/55 was washboarded a year or two ago, making any ride anywhere on the road more stressful than it once was. (The washboarded section includes but is not limited to Delaplane Grade to Rt. 50.)
Fortunately, the half mile or so heading west (uphill) on 50 wasn't washboarded, but it was trafficky and freaked us all out.