A seller will always try and resolve a matter with a buyer who leaves a negative feedback.
Actually they do not know feedback rules, because you mentioned a refund, and that breaks feedback rules, the seller could call Customer Services to have it removed.
The excuse for cancellation was out of stock, this will bring a damaging defect to their account.
If you are happy to leave that feedback than do so, if you wish it removed, ask the seller to send you a feedback revision to complete.
@sharondonkin04