Sorry, I went to bed and it’s been a busy morning here.
The specific arc you want, a full quarter, doesn’t work with my method, I’m guessing because the last couple of vertices are too close together for sketchup to work with. Those same bits Dave referred to earlier. A tangential arc will work but won’t correctly represent what you are trying to model.
So @DaveR 's method is better.
Edit: And sure enough, by using The Dave Method, mentioned above, my version works too. So it is a tiny face issue at the point of the roundover.