Content restrictions on mobile device (such as an iPad or iPhone) will interfere with the DUO 2-Step Panel, and prevent the iFrame from loading properly. Please disable parental controls or content restrictions on your device and try again.
For instructions on checking content restrictions on an iPad, see the Duo website: https://help.duo.com/s/article/3710?language=en_US
- check that there is no ad-blocker in Safari
- check that there is no installed profile/mdm/VPN that is unfamiliar