There it is in a nutshell!
Exactly what I have been seeing with mine
And yes that is a normal day on Lake St Clair and 15 miles is normal as well I did several runs today that were more than 8 miles each
If I had to guess the buttons are too sensitive and a good jolt from the ride causes one or more to make contact and this cancels the navigation
It’s a shame because it basically renders the Huminbird navigation useless thus the reason I run a Garmin just for navigation