I bought an item from NPC but not in my inventory. Please help

Hi,

I just bought an item from Stone Guard Mukar, Titan-forged rune of determination just now. I can't find it in my inventory.

I know it isnt much but I really tried hard to save up the Wintergrasp mark of honor.

Please help. Thank you

I think if you provide a screenshot of you buying it with your bag open, maybe you can get an answer.