Please check whether you are using a Lazy load or image compression plugin, such as WP-Smushit. These plugins will stop the custom meter loading.
All good lazy load plugins incorporate a whitelist function, where you can tell it to ignore specific images. If you are using WP-Smushit, follow the instructions below. If you are using an alternative, please contact the support team for that plugin.
Whitelisting Ultimeter in WP-Smushit
Head to the ‘Smush’ dashboard, and select ‘Lazy Load’ from the menu. Navigate to the bottom where you will find a box called ‘Classes & IDs’. Enter the Ultimeter class in that box: