Changes to values in custom profile fields on the first page of event registration are not propagated after 'Going Back' to the first page then 'Continuing' again.
To recreate on the demo:
1. Click the registration link for a free event that has custom profile (e.g. 'Progressive Supper' currently on the demo)
2. Enter primary email and values in the profile fields. Click 'Continue'
3. Click 'Go Back'
4. Change the value of the primary email and change values in the profile fields. Click 'Continue'
Observe that the new primary email is displayed, but the values in the profile fields remain unchanged at their original values. Also note that if you click 'Go Back' you will see the changed values on the first screen.