I'm running into an issue where only a small amount (< 10) greys are selling when opening a vendor window. I can work around it by closing the vendor window and opening it again until all greys are sold.

I'll try to reproduce it and find a fix for that.
Unfortunately I'll be out of WoW untill next week, so it may have to wait untill I come back.

Can you check if v1.4.1 fixed this issue?
For now I consider this closed.

I have not noticed the issue happening since then, thanks for your help!