I also had that Problem for a long time and tried a lot.
The only thing what brought a big improvement, was when i deleted all my history data O-:
Before that, the only what helped for the short moment was to open a new 2d map on map menu.
In my case:
- there was no significant change if i used network or not.
- the plans missing on 2 D were definitely in range (after takeoff on nearby cologne airport.)
- the flights completely appeared in the interface immediatedly after takeoff, also in the 3D map, but only after long time in 2D.
- it dident matter if it were high or low traffic times.
- the problems appeared when the system was running for a while.
- I got an XP 32 bit system with an intelE8400