$wpdb Object error

I use $wpdb Object to talk to the database and handle some of the functions in the form on this page. https://www.cmslaser.com/laser-capabilities/laser-marking

It’s the blue form on the right

I’m calling wpdb() class

When I use $wpdb->update I can’t get any data to populate in my database.
Connection seems to be fine

this is where it’s having problems

<?php $wpdb->insert( $leads_table, $data, $format ); ?>

Let me know if anyone is having similar issues

Thanks
Dmitry