So I have had the 1040 crash a few times while calculating routes, most recently a 326km route I was riding at the weekend. I started the ride and let it calculate while I was riding as I knew which direction I was going at the start.
Multiple times it crashed at 39% after hanging there.
A google search suggested that it was due to an error with the mapping. Turning the maps off in activity profiles - navigation - map - configure maps and just leaving the worldwide DEM basemap on solved it, the route calculated very quickly and although I lost most of the turn by turn instructions I could follow the track on the map screen.
I hope deleting and reinstalling the maps through Garmin Express will fix the problem properly now I am back home - I will update this thread
In the meantime, I'm sharing here in the hope that this gets indexed to google for anyone else stuck and frustrated at the roadside.
