Enhancing Naru Gear to +15 causes you to be unable to complete the quest. As far as I can tell this is a permanent fail of the quest and therefore seasonal. 

Fughar does not give out Naru gear regardless if you have enough time pieces in your inventory. This further makes the completion of seasonal impossible. 

Time Fill Stone Reads;

- Characters that have completed the Serendia Main questline can go to <Crow Merchants Guild Chief Manager> Fughar in any of the major cities to exchange this for Naru Gear

x1 Armor

x 5 Accessory

Except... no you can't. Fughar won't take it. 

What? When you enhance gear past the point you were asked for in the season pass, you can just talk to the black spirit while you have it equipped and it will complete the season objective. Thats been this way since like the second week of the first season.

dude youre a life saver, ive never over enhanced the gear (for the pass) before and i was like... this cant be bricked!?

Hey, having the same issue, over enchanced my Naru main weapon, and i'm now unable to progress in the season pass (Advancing Adventure Gear 3). Alredy tried upgrading a new main weapon to +15 and talking with black spirit with it equipped, no chat option appears. Any help would be very much appreciatted. Thanks!

It should auto complete now even without talking to the black spirit. But the way I understand, you already turned your Naru Mainhand into Tuvala? Even then, the black spirit should be able to complete it. Can you cross check that you accepted the rewards for all previous entries in the season pass? Sometimes that blocks new completions.

If it doesnt help, send a ticket to support so they can check if something else is wrong.

Hi, thanks for the reply. I've accepted all the rewards, i'll now be sending a ticket. Thanks again!