Permalinks with "jordan" returns 404?

I manage a blog site that will return a 404 if I have the word “jordan” anywhere in the permalink. In troubleshooting this, I’ve created a brand new post with “jordan” as the permalink and I get a 404. I’ve gone back to old posts that work and appended “jordan” on the permalink and it 404s that link. For example:

myblogsite.com/2016/04/jordan/ (404s)
myblogsite.com/2015/12/whatever-the-link-is/ (works)
myblogsite.com/2015/12/whatever-the-link-is-jordan/ (404s)
myblogsite.com/2014/05/whatever-the-link-is/ (works)
myblogsite.com/2014/05/jordan-whatever-the-link-is/ (404s)

To make sure I’m not crazy, I also appended “jordan” to the permalink on other WP sites on the same host with varying results. In one case, I get the exact same result, Page Not Found 404. In another case, the main content body won’t load. And in a 3rd case, appending “jordan” to the permalink works without a problem.

I haven’t had any problems with WP in a long, long time. Maybe this is just a coincidence, but I also just upgraded to 4.5. Any idea what’s going on here??