I tested this using GG Pickaxes, into Fyrds Treasury.  Everything actually works normally, but the inventory report is wonky.

Add 1 it says 0, add a second it says 1, remove one and it still says 1.  Remove the second and the entry goes away as expected.

This would be very, very low priority.

As I said on the PM, the treasury is not wrong, the tool is wrong. Why does it have quantity 0?

3 hours ago, Chewett said:

Why does it have quantity 0?

Obviously I don't know.

Mur, all I can do to test, if you change qty=0 globally, is on the same order as what I did with the pickaxe.  I don't have access to all the tools I see, and don't even know where to find some others.  I don't know about all the things that might go wrong.  So, I'm not in any position to tell you that I can test it all out.  All I could do is test some specific thing.