In an interesting post on GitHub, the user tkrotoff has apparently contacted Bing Webmaster Support with questions about why Bing Webmaster Tools will not accept his website’s sitemap file. He is trying to tell Bing’s Webmaster Tools about his sitemap file and it give him an error when he submits the file. His website, https://osteo15.com/, uses HTTPs SNI (Server Name Indication).
One response he gets from Bing Technical Support is that it’s “apparently a server issue which could be addressed by your web host provider”.
Then he got another response, saying that they would forward it to their research department.
It’s been several weeks now and nothing has been received.
He has tested Bing’s lack of support for SNI by moving one of his websites and turning off SNI…and was able to verify the sitemap in Bing Webmaster Tools.