I'm not sure if this is a bug or if there are limitations I don't know.

So I had over 50 clay in my inventory (I can't remember the exact number). I only have level 1 warehouse. I went to buy 100 more clay from the item trades. But when I checked my inventory after buying the 100 clay. I noticed that it says I only have a total of 100 clay. But my silvers were deducted and it actually did say that the clay was purchased.

Is this a bug?

Charix, according to the logs, you had won one Clay auction on the May 12th for 1000 silver coins, and this auction had 10 Clay, not 100.