acanthis is correct in that the products in Prime Time unleashed are excluded from coupons. Unfortunately, it was not clearly stated in the promotional article for the sale.  This has now been amended. https://www.renderosity.com/article/31280/prime-time-unleashed-72-hours-only 

This particular promotion is for our Prime Members and includes products that are not part of Prime but are marked down by a generous 65%. 

Because of this deep discount, coupons are not eligible for this promotion. We consider this a meaningful offer in its own right and hope you’ll appreciate the value it provides.