Did you forget to choose what type of equipment u want to build by pressing Z? (or maybe u changed it)
To start you'll need a new hammer (almost) every time you get to a new metal - Customer buy what your hammer level is or cheaper - Alloys are an exception, which unlock all metals (seemingly)
Additionally. if You're trying to hit heated ingots on the anvil and its not connecting or it is but its not making the right item associated with the right number of ingots, Then something may be in the way of the anvil, or, the anvil may have accidentally swallowed a heated ingot at some point or encountered a hiccup where it assumes it has.
I don't readily know ways to fix this - But you can try taking a pole grip and swishing it around inside the anvil, then removing it from the area, or using your crates near the anvil and seeing if you get a reaction that allows you to close it, and then trying to pull it away.
If you know you have a bunch of objects near the anvil, Simply first try clearing the space of these objects, An item may not even appear close enough to the anvil to count, but in reality, its hitbox/connection triggers are actually in the way and you just can't see it (possibly)
Then the next time you put up ingots open the radial and ensure the correct Group is /possible/ even if it is selected.
You'll see "Large Blades" for example if you have 3 heated ingot on the anvil and go to select blades.
If you see "Large blades" and only have 2 ingots on there - The anvil must assume there's another despite there not being. (Again, Aside from fishing around into a solid object, I don't really know what to do here)
If you have 3 on there and only see "normal" or "Small" - then something is blocking the Anvil from reacting properly to the other ingots. - Example - If an item is sitting ontop of one of the ingots - The anvil will not react properly. This is a readily apparent example - But It's possible a grip could be near by and causing an issue too, even not being near the top of the anvil.
I dunno if you've seen other posts yet where this was addressed, but
My Recommendation on Customers asking for shields is to only provide them with a shield, or only with a weapon, and not both.
The game can be saved after they pay and you can reload to clear stuck npcs away - but - If you only give them one or the other, and not both, you can simply dismiss the customer with the X button that you see when looking at them, and they will pay for whatever you gave them.
I assume, while it isn't verified as I don't really know code and haven't really seen it.
That its essentially an issue with how new the change is - More than likely, The Customer is told to "Wait for item" - normally - This would be "satisfied with weapon/item" and they would leave - however a customer asking for item and shield is told "Wait for items" and when they take one they are reinstructed to continue waiting for the other item....
But then they get the other item, and they're reinstructed again, to wait for the other item (which they already have)
While at the same time, they've accomplished "Wait for items" - and thus, begin to "clear out" - Thus their order and X button disappear like they're about to leave, they pay out, but then realize they've been order to "Wait for the other item"
By this time "The other item" is "Null" "N/A" because they have no Order/request - OR - Even if it remembers the other item is "This" - Their request is already "completed" and they no longer can "update" from "waiting" even if they can verify they have the other item.
Either way, They become stuck, indefinitely, because the order is gone, there is no timer, and no X, they can't accept items, because there's either no items that fit their order, which is to say, no order, -- or -- They already have both items, and know they've already accepted it, so they can't take all your iron swords in a single trip to the shop and only pay for one kinda logic.
Anywho. Point being.
If you have only for example
Copper and no Tin.
Sell them the shield - and then dismiss them for the profit of the shield - which is the most profit you can earn "on tier", I believe.
If you have for example - an Alloy hammer, and they request for example, Mithril, but you yourself only own 1-3 adelite ingots and 7 iron ingots - Then if you have enough to give them an Adelite version of the weapon they requested - you'll get more money, so give them that instead, and then dismiss them.
If they instead request "Mithril greathammer - with a (quality) grip...." - Just Dismiss them. unless You can give whatever weapon they're requesting. - As for the Shield, I dunno, You might still be able to give them a shield, but It'd probably be easier to just dismiss them.