This is a pretty common issue that's been addressed before, and it typically comes down to a problem getting Jeff, the junior reporter, close enough to Phil, the subject, to fire the dialog the first time he shows up at the settlement. for whatever reason, the AI package for this quest can hit a routing problem with the nav mesh where the route to get the former boy reporter close to the subject isn't clear and it just "gives up" and stops trying. this is mostly caused by something like a plot "blocking" the pathing between where Phil spawns and where the subject spawns. if you've ever played a Bethesda game before, you know pathing is one of those things that falls over if you look at it too hard.
if you've been through this quest before (or aren't interested in the interviews) you can use SetStage
to tell the quest (SS2C2_ConcordQuest_VoiceOfTheCommonwealth2ndEd_Alyssa
) that the interview is done so you can go back to Alyssa and complete the request. the stages in question are 25
for Phil and 35
for Dahlia. (the console can be dangerous, and if you are having trouble putting the command together from my hints, you probably shouldn't be using it)