Recently I've installed Moodle on a new IIS server to work with the last version (Moodle 3.1.1). I copied the "Essential" theme folder to moodle/theme. Then I've successfully installed theme - Site administration>Notifications. But when I go into the Theme Selector, the new theme is not in there... "Clear theme caches" or "Purge all caches" buttons don't resolve the problem... Please help!