I just came back from HOLs using my Nüvi 1490 with this new MAP to Seefeld - Tirol Austria.
By the return on the same road (Mountains road), my Garmin went crazy and couldn't find my position anymore during at least 20mins...
After 2 power off / on, it was good again!
However, with the Car's GPS (Nissan Qashai), also Garmin Map I guess, I do not have this issue.. Maps from the car are quite old than my Nüvi... Just wanted to share with you this strange behaviour.

Nüvi 1490 software version : 6.20
GPS : 4.30
all are up to date