It's visible for ADMINS only at bottom of frontend pages ( shop/category/cart/checkout/..).

You must visit >WooCommerce>Pricing Rules, tab >Settings>Debug and turn it on.

Tab Get system report

if you have PROBLEM with the plugin , click on "Get system report" and submit report/file to helpdesk.

It will save a lot of time for us. 

Don't forget to add some screenshots too :)

Tab Rules

This tab shows applied rules and timings for them.

All rules clickable , so you can edit wrong rule.

There are  2 sections

- Rules were applied to cart items

- Rules were applied to visible products

Tab Cart

If you have non-empty cart  - you will see items and which rules changed prices or added free products.

Tab Products

If you're at shop/category page  and option "Don't modify prices" is off   - you will see processed products