Bug: Cannot progress Leader in Dungeons

Rend Blackhand dungeon is completed at Level 23 but for some reason one of my Blackrock slots is only +2 or Silver Level. I have now surpassed the levels and do not seem to be able to get it +3 or Gold level. Any ideas? Thank you in advance.

Additional information: I levelled one slot to +4 or Diamond and Upgraded to Wildcard prior to having the Dungeon and Leader slots complete to +3 or Gold. This may have affected the ability to upgrade. Please investigate.

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