guild socketable stash upgrade

I have an inquiry.

I bought the guild socketable stash tab, but I can't activate the upgrade button as the message pops up.
Access this feat by completing the quest "Treasure of Utzaal" in Act 3.
I've already completed the quest.

Same problem here, made sure I had it completed on both difficulties and still can't upgrade

This is also happening to me. I actually completed the quest in Act 3 while this message was displayed and it did not grant me access to said tab. (Have guild stash tab for socketables). Am very upset my guild spent real world dollars specifically for a feature that doesn't work and it has pretty much killed the enjoyment of the game for our guild since.

Additional Info:
I have a few characters running maps on default League and have completed this quest in both default and Dawn of the Hunt leagues with characters prior to our guild buying the tab. Everyone in our guild has completed this quest at some point. Since buying the tab we have had guild members complete the quest indicated and it still did not fix the error message.