Same here, no issue on my main Hunter but on my secondary Titan, it's requiring the quest to be done. The problem is that it's saying my quest inventory is full. However I checked and I have 23/63 Total Quest and Bounty Capacity. I have tried abandoning a couple of them just for shits and giggles but no luck.
Just saw a reply on another thread
"Access the first Forsaken mission in the Quest Archive Terminal at the tower (it's in the Past section)."
Checking I'll post here again if it works
**** It worked ****