Your promotion worked. It borrowed the sales from the shelf next door.
Roughly 72% of trade promotions never break even (McKinsey). Uplift gets counted gross, so the shelf next door quietly pays for the win. The promotion lands and the stock doesn't. And every promotion costs something on the full-price business that nobody ever measures.
What changes on Tuesday.
Cannibalisation modelled, so uplift is net rather than gross. Promo ROI with the replenishment actually behind it. A price-integrity penalty, so you can see what a promotion costs the full-price business before you run it again.
The proof: The promotion was a success. The stock never arrived. Both things are true. The replenishment for a promotion is sized inside the same horizon as everything else, with the promotion in the run rate.