The quest requires you to "Enter the Site of Power" but does not get marked as complete when doing so. I've completed the site of power and moved on to the next zone but the quest is still in my list.
Edit - It appears completion of this quest is nessecary to get the card to open the swamp gauntlet.
I have the same problem. I've gone through the fight 3 times now at the Radiant Site of Power and entered the Heart. I have the Mystic weapons unlocked in my Progression tree, meaning I've completed the trial and exited the Heart. Glorious Hunt - Reach the Heart is still set to 0/1. In the screenshot, I have opened the portal, taken the essences, and you can see my Mystic weapons equipped. How do I complete this quest an move on???
Thanks to another post, I found out there are infact two sites of power, The quest does not reflect this. Entering the other one was able to trigger the progress for me.