In this playthrough I have yet to complete the mission on Cyone, but the game has marked it as having been completed and I received the e-mail from Riley that you get after completing the mission. Are there any variables I can adjust to make the mission available again?
It does not sound like you have the same issue as the op of this 6 years old thread.
The issue described in this thread is that the "Fuel Reactors" Mission was set to complete in the Mission log before it was completed.
What is you exact problem?
On what system do you play?