Customers won't take shields

[Polar_Kollar]

So I keep getting customers asking for copper x item and a round shield. They will take the one item but when it comes to the shield they just stare at me like I'm some sort of moron.
Am i missing something or is this a bug?

[derpygamer2142]

I saw this too, does the quality of the shield say "Unavailable"?

[Polar_Kollar]

No it has a quality rating.