I'm not shure if is it really related with the theme or the framework used for the theme options but I had to downgrade to previous version of Wordpress. I experienced this same malfunction when upgrading other installations and stopd the propagation of this version in other installs. This 4.7 version seems to be the most problematic experience of my Wordpress upgrades.
I suppose some script break ajax request on all admins page. This script insert <?php to beginning of response. It looks like some plugin works incorrectly. Try deactivate plugins one by one and check theme options page to find what plugins make this.
I'm not shure if is it really related with the theme or the framework used for the theme options but I had to downgrade to previous version of Wordpress. I experienced this same malfunction when upgrading other installations and stopd the propagation of this version in other installs. This 4.7 version seems to be the most problematic experience of my Wordpress upgrades.
Hi,
I suppose some script break ajax request on all admins page. This script insert <?php to beginning of response. It looks like some plugin works incorrectly. Try deactivate plugins one by one and check theme options page to find what plugins make this.