Since sending a bug report failed, I'm doing this in the forums:
I just finished the story missions up to "Crack in the Mirror", but Captain Kurland doesn't offer "The New Link". I tried hailing him, walking up to him and have now entered Orias without the mission.
I have just entered Orias system without the mission and apparently, I now do have the mission, even though it's grey.
Edit: Finishing the mission did not continue the storyline, but I could accept the proper mission afterwards with rewards.
Edit 2: Seeds of Dissent not available afterwards, except for being able to beam up Water Purifiers from DS9, but I was offered that option for quite some time... Only this time it actually gives me the mission (grey of course) when I enter DS9 area.
Edit 3: Aprpoached Seeds of Dissent the same way as I did with The New Link, however it did not unlock after finishing the mission this time.
Editi 4: Played Stranded in Space and Diplomatic Orders again, Seeds of Dissent is now available.