Looking here, your not the only one reporting problems:https://www.waze.com/editor/?zoom=4&lon ... TTTFTTTTFT
Taking a quick look, I found a couple of nodes with reverse connections. I fixed those, but I don't think that would cause this many problems. Maybe someone from CA can take a look who would know better. Looked like someone was in the area updating on Dec 5, so if there was a problem that was fixed, it should have made the update on Dec 10th.
To set start and end points on the live map, you can left click on a road and you get a bubble with choices of start or end point.