yes, that’s very strange indeed. Can you inspect your page to see if you get any javascript errors in your console?
can you also turn on WP_DEBUG using the following lines in your wp-config.php file,
define('WP_GURUS_DEBUG', true);
define('WP_DEBUG', true);
if ( WP_DEBUG ) {
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
@ini_set( 'display_errors', 0 );
define('AUTOSAVE_INTERVAL', 600 ); //seconds
}
this will create a debug.log file in your wp-content folder. Please see if you are getting any PHP errors too.
Let me know your findings.