Troubleshooting: Discounts not stacking

If two discounts that should combine aren't applying together, the cause is almost always a combination rule.

The fix

1. Open Cart Editor → Settings → Discount Settings and make sure the right boxes are ticked, then click Save:
   • Combine with other Product discounts — free gifts, Frequently Bought Together, volume and upsell discounts
   • Combine with other Order discounts — Discount rewards
   • Combine with other Shipping discounts — free shipping rewards
2. Open Shopify admin → Discounts.
3. Click into the other discount that's not stacking (for example your discount code).
4. Open the Combinations section.
5. Enable the right combination types:
   • Combine with product discounts
   • Combine with order discounts
   • Combine with shipping discounts
6. Save.

Why this isn't an Oxify bug

Both discounts have to allow the combination. Oxify sets its side from the Discount Settings checkboxes (all on by default) and re-applies them every time you save — so change them in the Cart Editor, not in Shopify admin. The other discount's side is set in Shopify admin. If either side doesn't allow it, Shopify keeps only one of the discounts.