Hi Glennyboy,
Thanks for writing in! The Customizer is kinda live editor and takes place on the front end, so sometimes Cloudfare tries to cache its resources. This can cause stale data to be loaded. To resolve this, you’ll need to disable Cloudfare when the Customizer is in use. This won’t effect front end performance at all.
1. Log into CloudFlare and navigate to “Page Rules”
2. Add a new rule using this URL pattern: *.example.com/customize.php/*
3. Under custom caching, enable “Bypass cache”
4. Turn Performance “Off”
Replace example.com with your site URL.
If you’re still having issues using Customizer, you may need to login to Cloudfare again and purge the cache.
Hope this helps.