Why some of my points are marked as incorrect or "Path not Found"?

A "Path not Found" message usually tells you there is a problem with one or more stops on your route and that stop/stops can’t be accessed by the public road (they are on an island, in a forest, really far from other stops). This case is pretty difficult to resolve with optimization algorithms automatically, so that will require some manual check of those stops by a user. To help you to resolve this, the app will mark stop/stops with known errors and can even exclude them from the optimized stops sequence.
P.S. There are some cases when the app can't show an error on a stop because there is no clear reason why. In this case, the app will rely on a user to check all stops manually and figure out those which do not look correct.
Vehicle type issue. Also, it can happen if your vehicle type is a big vehicle like a truck. The error will appear when the optimization algorithm and/or navigational services do not see any ability to build a route for this type of vehicle to one or more stop/stops (low bridges, narrow roads not suitable for a long or tall vehicle, etc.). This case is easy to resolve by changing a vehicle type to a car. Do not worry, the majority of vehicle types will do just fine on routes for a car, it is just those trucks which are really long, tall, or big that are going to face issues and absolutely must use truck as a vehicle type.