I am having the same issue as a previously opened ticket on here. Just bought my 8theme and installed it today with all the required plugins. I have not edited anything at all and this is a fresh install. The 8theme customization options won’t let me save anything. It keeps opening a dialog telling me there is a problem.
There is a line in the code that is also causing internal 500 errors for theme customization and deleting plugins. When I deactivate the theme, I am able to delete the plugins.