Two campaigns are live, but shoppers only get one

Two campaigns can both be live and both be working exactly as built, and shoppers still only ever receive one of them. That is not a bug in either campaign. It is what happens when two discounts are not set to combine: Shopify applies the single better deal, never both. This page shows you how to recognise it, confirm it, and fix it.

What it looks like

• Two campaigns show as live, a cart qualifies for both, but checkout only applies one discount.
• The discount that applies is not the one you expected shoppers to see.
• The free-gift variant: the gift widget adds the gift to the cart, but at checkout the gift is charged at full price because a bigger discount won instead.

Why: the better deal wins

Every Stackable campaign publishes as its own Shopify automatic discount. Whether two discounts apply together is set per campaign in the builder's Stacking step: a campaign either runs on its own (Solo, the default) or opts in to combining with other discounts by class - product, order, or shipping. Combining is mutual: BOTH discounts must allow the shared class, or they do not stack.

When two eligible discounts of the same class do not both opt in, Shopify never applies both. Checkout compares them and gives the shopper whichever one is the better deal. This is Shopify platform behaviour, not a Stackable choice, and it applies to every pairing: two Stackable campaigns, a Stackable campaign against a native Shopify discount, or against another app's discount.

How to check

You do not have to discover this from a shopper complaint. The app surfaces the conflict in three places:

• When you activate. Activating or resuming a campaign that overlaps live discounts it cannot combine with shows a warning on the Campaigns page. It names up to three conflicting discounts ("runs at the same time as X and they don't combine - shoppers get the better deal, not both"), plus "and N more", with a link to the Discounts screen. The campaign still activates; the warning is a heads-up, not a block.
• The Discounts tab. It lists every discount running on your store, including native Shopify discounts and other apps' discounts, and flags the pairs that conflict.
• The simulator. Build the exact cart you are testing. The simulator honours combination rules, so when two discounts cannot combine it shows the better deal winning, exactly as checkout will.

How to fix it

1. Let them combine. Open the Stacking step on BOTH campaigns and allow the shared class on each side. For the free-gift example: the Free Gift campaign must allow product discounts, and the "buy 2, get the 3rd free" campaign must allow product discounts too. One side alone is not enough.
2. Or keep them apart. If you do not want the deals to stack, do not run overlapping Solo campaigns of the same class at once: stagger the schedules so they never run together, or narrow the targeting so no cart qualifies for both.