I see your route has worked, but it does not use the same airways I had a problem with, the first being N437A, the second P600, so whilst you have been fortunate, it is not the same route and therefore cant be compared.
The route that I had a problem with was a route generated just yesterday using PFPX which has also been updated and I do not use any stored routes. In order to as not pin point PFPX, I also have had problems with simbrief generated routes.
Seems several users are experiencing something similar. And I have indeed rebuilt both the sim and the airac data.