As of April 15, 2020 OneClickUpsell checkout supports Shopify "Automatic" Discounts 🎉
Notes and limitations of integration with Shopify Automatic discounts:
1. If you're using an Automatic discount and pre-purchase upsell offers for OCU, then we recommend enabling the "Apply Shopify Discount Coupons on Pre-Purchase Offers" setting within the OCU app at Settings > Pre- Purchase:
2. If you are using an Automatic discount, we do not recommend using a Fixed or Percentage discount in OCU for product(s) added as a Pre-Purchase upsell offer.
If you do, then the Automatic discount won't be applied on the Pre-Purchase offers that have a discount in OCU, but it will still be shown on the cart page. We are ignoring the "Apply Shopify Discount Coupons on Pre-Purchase Offers" setting for this case only.
3. If you are using an Automatic discount, we recommend to use the Compare at Price option as the discount for the Pre-Purchase upsell offers. That will allow the Automatic discount to be applied correctly to the pre-purchase offer(s).
4. Automatic discount performance/usage-count isn't updating in Shopify admin because of a Shopify API limitation. The usage number for your Automatic discount won't be updated when an order with an automatic discount is created and imported by OCU.