I have travelled some 8.000km with my camper in combination with MRA, without any problems.
In the planningstage, it will simply reroute when you have a violation. You will not be warned. And don't be stubborn and try to push the route somewhere it isn't allowed or can't drive through. I had this with a route, tried to reroute by inserting waypoints, but route was terrible. Streetview showed, that I wanted to pass a tunnel with a height of 2,75m. My camper is 2,95m
In ridingstage, I have never had this warning, when following the route. I once had to take a detour and had this warning. In this case I was not allowed to pass a road because of the weight. The app recalculated and everything was fine.
I agree with @Marinus-van-Deudekom check the position of all your waypoints. You must work very precise making a tour, or you get a lot of unnecessary warnings.