I had this exact same thing happen with one of my characters (I hadn't used him in forever), but it turned out fine when I went ahead and just did the quest anyways. No glitches occurred afterwards -- Ponydale still stayed "warmed up", I got my snazzy vest, and the quest completed normally.

This happened to my Artisan earth pony. I finished my Artisan quest, then went to graduation (though I don't think I spoke to Frizzy before graduation). Now she has a ! above her head, and my journal also shows the "(Optional) Talk to Frizzy Stradlin" objective unchecked, although the quest itself appears complete.

I guess you can add me to the list of "people who have reproduced this issue" since I submitted it in http://phabricator.legendsofequestria.com/T2334 (I didn't realize until later that someone else had also submitted it). Hope it gets fixed soon!

UPDATE: After some experimenting, it seems this boils down to a MUCH simpler glitch: If a crafting item is placed in the final inventory slot, then it will not appear as "available" when you open a forge or workbench. I confirmed this by moving items in and out of the final slot, and I could see the "available ingots/cloth/etc." change in real-time in the crafting screen.

On a related note...I noticed that if the Linen Padding was after the Bronze Ingots in my bag, then they (the Linen Padding) also did not appear on the Workbench page: https://i.imgur.com/xMz57oD.png
Once I moved the Linen Padding above the Ingots, then the correct amount appeared: https://i.imgur.com/z6YMVJC.png

Update: Within the past 30 minutes or so, I noticed that my forged Bronze Ingots began stacking up to 40, which is a huge improvement! Not sure if the glitch is completely solved, but it appears to be getting better.

In T2334#34672, @pavmarkarov wrote:

Heeey, welcome to our club, pal)
http://phabricator.legendsofequestria.com/T2316
http://phabricator.legendsofequestria.com/T2313
It appears to be an old-version NPC-bug (check my screenshot)

I have been able to consistently reproduce this glitch as well--it happens no matter what I level up (combat, flying, partying, etc.). This glitch has been around for a few months--I'm not sure how to refer to similar cases on here, though. Hopefully the team is already working on it!