If your Pop Up Blocker is enabled on your browser, you may experience issues using the Two-Factor Authentication during sign in. Some browsers allow the pop up blocker to be disabled for a specific website, and others require that it be disabled for the browser as a whole.
Below are steps for managing Pop Up Blocker settings on many popular browsers and device types:
Desktop/Laptop
Mobile Browser
Mobile Chrome Pop-up Settings (follow "Allow pop-ups for a specific site")