I have been taking this route from Bake Pkwy & Rockfield Blvd, Irvine, CA 92618 to irvine blvd and sand canyon ave, irvine, 92620 since I have joined Waze and the only time it offers the route is after I pass the Toll road 133.
I have never received an alternate route for this route, even though this is the only way I have traveled to this destination.
And this is since June? You have the "Work" location set in the Drive To menu? You do have the "learn frequent routes" setting enabled, correct? If so, this is quite odd as that should be more than enough time to learn the route to your Work location.
And as Chris suggests, when you say "never received an alternate route" does that mean you do bring up the alternative routes to check if it shows there?