I was having the same issue except that the “Update Rewrite Rules” button was missing altogether. I’m not sure if this means the issue you are experiencing has a different source, but here was mine:
Under “General Settings” I had “Site Address (URL)” as “https://mysite.com”.
When I added “www.” to the URL, the redirecting ceased it’s confusing and I know longer get any errors.
May be a long shot, but I hope this helps!
