A temporary solution could be commenting out the following in wp-includes/class-wp-customize-control.php:
foreach ( $this->settings as $setting ) {
if ( ! $setting->check_capabilities() )
return false;
}
so it will look like this:
//foreach ( $this->settings as $setting ) {
// if ( ! $setting->check_capabilities() )
// return false;
It may end up listing options that the theme doesn’t support, so it can lead to problems. Once the author updates the theme with the fix ensure you will revert this change back, for this check is part of wordpress.