Problem at this location https://www.waze.com/editor/?zoom=4&lat=34.1731&lon=-118.5964&layers=BFTFFTTTTTTTFTTTTTFTTTTFT says that most users do not follow the recommended route. As there is no street segment which matches the recommended route, I do not know how to fix the problem.
The MP was generated by old data (someone has already removed the incorrect segment) - just mark it as solved.
Edit: That parking lot should probably be mapped as a Parking Lot and not Private Roads - and that segment may need to be restored and done properly.