Really weird it happen to me too, I made a custom order for someone and now they are no longer on etsy when I try to convo them it says "We're sorry, it appears that you're trying to send a message to an account that is no longer on Etsy."
Silly me I did not put a watermark. I have sold items to them before, so I thought it would be ok.
Let me know if you figure out how to deal with this.
Good luck to you with this prob!
Malvi>^,,^<