It sounds like you have just Shaping Points between your start and end points in that case. If you have Via Points, they will be listed as available choices when you hit GO. But whichever point you choose, the satnav will create its own route to the selected point. It will not follow your plotted route, until you have reached that point after which it will continue along the remainder of the planned route. This is handy if you want to restart the route part way through - eg after a break for example. I cover this scenario in some detail in a lengthy document I have recently posted.
It can be very difficult to guarantee that you are actually at the precise start of a route. I learned that very earlly on when my satnav used to try to take me the wrong way out of our cul de sac when i started a route from home. Where i was and where the satnav had me located would be about 5m apart. In fact, with the Zumo 660, plotting a circular route was a no no. It would stop navigating as soon as you set off - because you had reached your destination! Setting the start as a point that you will travel through once you have set off is a good trick to use. Even somewhere 5 miles up the road. It is a technique that works well with the modern Trip Planner Zumos.
There is a lot if misinformation about profiles in Basecamp and Routing Preferences in the Zumo. What you are saying may be correct for your situation, but it sounds like your Basecamp, Zumo, cradle and preferences are out of step with each other.
Again, i have covered this in section 4 of the document. But briefly....
Your car cradle is not a car cradle. Your bike cradle is not a bike cradle. When you clip the zumo into one of the cradles it switches the Zumo transportation mode to the mode that was last used in that cradle.
When you run a route, it switches the transportation mode to the profile that was set in Basecamp - car, motorcycle or off road. If any other profile is used in the route in basecamp, it defaults to motorcycle.
The avoidances are set separately for car and for bike in the zumo. Ie there are two sets retained. The avoidances are not carried over from any that are set in Basecamp, when you transfer and import a route.
It is also worth noting that when you remove the Zumo from a cradle, it remains in the mode that it was in. When i was testing this behaviour I found it handy to set the screen orientation of my 590 to portrait for the car mode and landscape for the bike. It was instantly obvious that modes had switched when i switched cradles. And it became apparent when switching from car to bike, how easy it was for the 'car' cradle to set the Zumo to bike mode, and for the 'bike' cradle to set it to car mode. It was so easy to slip up and not notice the tiny icon, that i decided never to use car mode. Both cradles behave as motorcycles, and i never use any profile in Basecamp other than motorcycle.
In the article i describe which settings are set globally, and which settings are set separately for the transportation mode in use. Those for the 39x series units may be different- but the article shows you how to tell.
Link to the post with the article is here - see post #1