Bing Webmaster Shows Domain without WWW

[rkdc]

One of our sites shows thousands of 301 redirects due to domain without www in Bing Webmaster under crawl Information page. It’s been like this for a long time. None of the internal pages have domain without www, it was tested through Screaming Frog. We do have www preference set in google webmaster, but unfortunately bing doesn’t have this option.  We also specify URL with www preference through structural data, but that still doesn’t help. Did anyone have similar problems with Bing, and how did you resolve it?