I first noticed this issue when loading saved navroutes I'd reversed by hand via text-editor:

reproduceable: always

steps:

- travel to (for example) Dau L-10
- /navroute add "Dau L-10"
- /navroute add "Dau K-10"

expected results: your next jump goes to K-10

actual results: the route shows up on the navmap, but you can't jump anywhere (as if you had no route set at all)