Yes i have Googled this issue and it has brought me to these forums. I have also found info on issues with other plug-ins, but not any plug-ins I have running. I’ve disabled plugins Akismet, Contact 7, Jetpack, and Wp Super Cache without better results trying to save menu items in customizer. Additionally i have another site running GP Premium on the same server with those same plugins (and more] running without this issue therfore I’m feeling like server configuration is not the issue. That said, what particular server configuration are you referring to? At this point I’ll try anything.