That is weird. Both the Android app and the Live Map find multiple routes, but the shortest and fastest route is listed as the second choice. This image sums up the issue:
It appears that your change did the trick. From this can I make the assumption that Waze will favor road segments that are at or above the “importance” of the road where the route starts and that is why it avoided the FM? Changing the importance of the FM fixed the issue or is there something else going on with the routing engine?
Now you see the importance of FC. Waze maximizes FC as long as it’s set properly. When we first looked at this area, the road was two way the whole way, but also had various degrees of road. It wasn’t consistent enough for Waze to route down it, so it took the FC route, which was longer.