when I make adjustments via the Customizer Front page – Services Sidebar I can not save it. If I change other sections of the homepage, I can save it.
(wanneer ik aanpassingen maak via de customizer Front page – Services Sidebar dan kan ik het niet opslaan. Als ik andere secties van de homepage wijzig kan ik wel opslaan.)
The page I need help with: https://energiecollectief.nu
WP 4.9.1
Hello there,
I hope you are doing well today.
Please go to Dashboard > Updates and install any pending updates available then use the following plugin to clear your WordPress cache:
Best Regards,
Support
^ This is not the solution 
Hey there,
In most cases you can solve issues with the theme customizer by disabling your plugins in the WordPress dashboard. You could try deactivating your plugins one by one to identify the plugin that is causing the issue and then just replace the specific plugin with a plugin that doesn’t cause issues.
Best regards,
Support.