Im currently working on my Customizer, and i just started off, when i reallised that there is a problem.
I added a new section, control and setting to change the color of h1, and everything works in the customizer. When I click on publish however, there is a red error box telling me that there have been problems with saving.
When I try to close the customizer, there is error message telling me that I have unsaved changes. When I close that, the changes I just made are still beeing saved.