I'm using LiteSpeed caching plugin
If you are using the LiteSpeed caching plugin, you should do the following settings in your WP to effectively capture UTMs.
Go to Settings
Copy the list below and add it in "Do not cache cookies" field
utm_campaign utm_source utm_term utm_medium utm_content gclid first_utm_campaign first_utm_source first_utm_term first_utm_medium first_utm_content handl_original_ref handl_landing_page handl_ip handl_ref handl_url organic_source gaclientid //and all the custom parameters created by you
Copy the list below and add it in "Do not cache query strings" field
utm_campaign utm_source utm_term utm_medium utm_content gclid //and all the custom queries you are capturing
That's it. You are ready to go collecting UTMs :)