Wellspring looks to be bugged for some people and not giving rewards. I have run wellspring three times (once on attack, twice defense), and gotten nothing out of the chest but glimmer every time. Additionally, the powerful reward was not rewarded to me either on the third completion, but the director was tracking my progress, and it is now gone from the director as though I earned it.
Others on reddit are reporting this as well: https://www.reddit.com/r/DestinyTheGame/comments/szveeq/the_wellspring_defend_weekly_powerful_not_dropping/