Red arrow on Mazda 3 satnav?

My mum has just taken delivery of a 2016 Mazda3. Recently on the Great Alpine Road in Victoria, the satnav screen was blank in some spots along the drive. The screen just had the red arrow and no road detail, as if searching for a signal. Have you, or anybody else, had this trouble? I told her to mention it to the dealer during the week when it goes back for its 1000km check.