On the quest for Transcended Crafter, if you craft the shield before you go and get the agave, Oztomeca won't accept the shield. This has not happened to me, but seems to be a known problem amongst crafters.
Yep I was a victim and I did this to myself. I don't believe it's a glitch as I believe one of the requirements for the shield so it wants to help you by giving you agave. So it requires you go to it before the shield will count as crafted.
I see how this can be considered a glitch but I think it's more one of those "don't jump ahead" kind of quests.