Because everyone is using their Fleet Carriers to move goods to build colonies there is a considerable queue/wait time (and regularly no slots) to move FC at the moment. The hamsters are doing their best, but it's not good enough.
It should settle down in the next week or so once the FOMO crowd either complete their colony or move onto other things/games.
edit : I should have pointed out just in case you didn't know. Wait/queue times only apply to Fleet Carriers not ships.
Wow that's a pretty epic fail. Get a bunch of people to come back, they immediately cannot do what they came back to do.
