Terminals Disappearing

[GamingWalrus1]

I was playing the game and some nodes I needed to access for missions disappeared off the map...is it a glitch? Do I have to abandon those missions now?
I had to copy some files from Primus and other places, but now I can only direct connect and that doesn't work too well...

[Aurora Yukihime]

On your Gateway screen, click the empty space (see the column of buttons over there?) to the right of the blue line containing the system you wish to connect to. Upon pressing it, it should become a blue square. Check your world map and it will be back.