It is not letting me install it and showing a price in the store. The other routes are showing owned and are available to install. A similar issue occurred in TSW2 for players who obtained it in Train Sim World Upgrade/Deluxe Upgrade (contained Rapid Transit and NEC). At the moment, the route is showing owned only in TSW2020 and TSW2.
Same with Great Western Express. Funny, because exactly the same problem happened with Rapid Transit on the last changeover from TSW 2020 to TSW2.