I spotted on ongoing thread at Bing Help where some webmasters are receiving the error, "It appears that you are not authorized to work with this site."
The issue has been happening to various webmasters since June of this year. Several other webmasters have complained of the issue but Bing is not sure what is causing it.
Will from Bing is asking those affected by this to submit a support request over here.
I am not sure how quickly Bing will discover the issue, if it is an issue at all. But they are promising to look into it.
Bing also has a sitemap pending bug which is still a current issue with Bing Webmaster Tools.
Forum discussion at Bing Help.