I am not using a wp cache (or any cache) plugin but changing fonts in the customizer yields no results.
Hi, can you share your page link? Do you use content delevery network, maybe cloudflare or something like that?
I’m afraid I can’t share my page link because it’s running on localhost under WAMP.
But I am not using any exotic extensions or plugins, including those you mention above.
I can’t help you then. Some sugestions: try from different browser, clear browser cache, deactivate all your plugins and check permisions for database user, reset WAMP (php and mysql) or your machine.