@albar965 : Just to be clear: I don’t think that this is a problem with Little Navmap export. As I also mentioned in the issue (on which I commented - the issue was raised by someone else):
I have an older flightplan (also exported with Little Navmap) which is known to have worked in around December 2020 (and January 2021, when I finsished my community flight “Tell Tours”) in FS 2020.
So I can’t say when the issue with the “disappearing leg segments” (navigation lines) started to occur in FS 2020.
Anyway, this is my original flightplan which used to work:
And here is a recent flightplan which still works (with the current FS 2020 SU 7):
As mentioned in the linked issue above I already tried to make those flights plans “as equal as possible” (with a text editor): in the end the only difference were the waypoint coordinates, their names (I tried to simplifiy mine as much as possible) and the amount of waypoints (in my case there are many more waypoints than in the “Canada” flight plan). But still I experienced the “disappearing legs” (which you can really watch happening as you spawn your aircraft and open the VFR map, with key V) with my own plan, whereas the “Canada” flight plan works as expected.
So I have little hope that there exists a “workaround”, except reducing the number of waypoints (or making the distance between them bigger - that may also be a possible reason). But maybe you have better luck and spot the critical point?