I'm currently playing my first game on a random small galaxy that looks like the symbol Infinity in which the only choke point between the AI and I was a pirate planet. My civ capital is in the rear and during the game, it suddenly was depopulated with the only explanation "We lost contact with the planet [name]". It wasn't a pirate raid or the AI since there was only 1 phase lane of mine leading toward to this choke point in which I also stationed my 2 fleets there (it's a plasma field). So I have no idea how my capital depopulated. Can it be Allegiance? But it was my capital so it shouldn't have this problem?

Can anyone explain to me how that happened?

One more thing, the game froze the first time I tried to load my game which forced me to close it and reran it. The second time was fine.