I moved a site to its final destination. There are two problems I can’t figure out:
1. The social icons, the search icon and the > in the menu are disfigured.
2. When I start the Customizer, the preview screen is blank, with an error message: “Non-existent changeset UUID.”
Hi, I faced today the same issue (preview screen blank and “Non-existent changeset UUID.”), appeared just after the installation of a SSL certificate for the domain. The problem has been solved setting the URLs in Settings > General with “https://” instead of “http://”. Fyi.