There is a known issue with Duo and users using Menlo Security software in which during the login flow the end-user gets an error page on Duo's site that looks like
The resolution at this time is to use a different device. Duo is working with the vendor to resolve the issue. This may effect users using devices issued by the Department of Defense, or Law Enforcement such as at Fort Leavenworth. There is not an estimated time frame on resolution at this time.