Infinite loading on Submit

I have tried all below:

– I disabled all plugins (except CF7) and switched to default WP twenty-sixteen theme, issue still persists
– There are no errors in console
– I’ve re-uploaded the latest version of the plugin
– I’ve tried this in plugin’s wp-contact-form-7.php file:
define( ‘WPCF7_LOAD_JS’, true);
define( ‘WPCF7_LOAD_JS’, false );

Still no luck — any ideas? To my knowledge, the information is being sent but the user is not notified or successful submission and is not notified of any validation errors (users are submitting multiple forms because they have no idea if it’s going through). We’re planning on activating a modal with a js DOM listener via https://contactform7.com/2017/06/07/on-sent-ok-is-deprecated/ but we need the form to submit successfully first.

Thank you

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