Can not complete desk registration on mobile device

Can not complete desk registration on mobile device

We are testing the new desk and setting it up for use.  In testing the portal, we clicked the accept button in the invite email on our iPhone, and it pulled up the form to set a password.  We entered the password and when we clicked the "Register" button it would not do anything.  Had to go to PC to complete the registration.

Is there a fix to this? As this is not convenient for clients.  Thanks!