I had exactly the same situation. Normally if I leave home with 90% I can get up to Ferrybridge with 12%. So I charged to 97% and the expected percentage at ferry bridge started off at 19%. As we went up the temperature outside dropped to below freezing and the anticipated arrival percentage started dropping. With 50 miles to go it was down to 13% even though I slowed to 60mph. The trouble, I suspect, was as it kept dropping and I kept slowing the pre-conditioning was going to be on for longer. I was down to 46mph and it was down to 5% but still dropping. It never suggested an alternate even though we sailed by Woodall as it (and I at the time) did not know one can access the southbound supercharger. Eventually I sped up and I arrived with around 7%. I would have changed the location but I did not want to miss my turning.