When using the Shopify Functions checkout mode, the app creates 4 automatic discounts in the Discounts section of Shopify. If any of these discounts get corrupted, cannot be created, or have been removed, you will see the following alert on the Discount Ninja Home dashboard.
To address this error, the existing discounts must be removed and re-generated. Go to Discounts, select all the discounts of Discount Ninja, click the ... context menu and click Delete discounts.
After this, go back to the Discount Ninja app, Settings > Checkout Options, and click [Fix missing discounts].
When prompted, click [Continue, I have removed the discounts].
The error should then clear out within the next 10 to 15 minutes.
Discount Extensibility
In order for any given Shopify user to benefit from the Shopify Functions checkout, the account must have Discount Extensibility enabled. You can recognize if your Shopify account has Discount Extensibility enabled by observing the Combinations column in the Discounts Section.
If you do not observe this column in your Discounts section, please contact Shopify Support in order to discuss your options.
In the meantime, the recommended checkout mode to use is Draft Order.