Thanks for posting your question here.
This particular message is actually just a warning, and does not provide any insight into why your listing failed to post. However, I see that this listing did fail to post initially and the you can see the error message which explains the failure by clicking the red number in the “Notifications” section within your account.
I see that you have since been able to locate this error and post your item successfully, but I figured I would update this thread as well for the potential benefit of anyone else encountering who may come across it that is experiencing similar difficulties.
If you need any further assistance related to this matter, please follow up with our Customer Support team directly through the ticket you opened on this subject and we will be happy to continue working with you.