Hi Andreas
thats a MSFS “feature” in the flightmanagement of the MSFS. You can’t really do anything, expect you enter the waypoint manually.
The reason is, that the FBW also use the same bad flightmanagement for the routes and therefore, there is no difference between the worldmap and the FBW (in the worldmap you can’t select VIA/transitions - ASOBO has simple forgotten this).
Also, its independet if you have installed our data or not. The same (if the procedures exists) happens with the stock data.