So I was given the task by the BOS to find three of their operatives. I put off this task for a while. Then when I'm ready to start this quest again, I can't.

The quest name in my quest list seems to be dim, an indicator that the quest was complete. But I didn't finish the quest. But the "show location" button still works, but when I click on it, no quest marker will show.

And this isn't the only quest that does this. Cass's quest also does this. I opted to try the peaceful path, so I went and stole both of the documents and then tried to talk to Jackson. No dialogue option.

Yep, that's another bug. I had a different problem with the same quest. I got the quest markers just fine, but the patrols I was supposed to find never spawned. Ended up having to use the console to skip to the next part.