One workaround suggested is to add the below CSS in Appearance -> Theme Options -> Custom CSS tab.

.parallax-section {
     position: static !important;
 }

Another suggestion is to add the below CSS:

.ios .parallax-section {
    background-attachment: scroll !important;
}

When using the above fixes, the Overlay background (e.g. “Dark Black”, “Light White”, or “Black Small Dots”) will no longer work on Safari/Chrome on IOS devices.

Using WordPress 4.5.2 + IOS 9.3.2 Safari + Chrome 51.0.2704.64 parallax background images still do not appear correctly, especially in portrait mode.