If a product is marked as unavailable in your payment form, it usually means that product quantity has been enabled and the available stock has reached zero.
For more details, see:
How to manage product quantity and availability
How to Check and Update Product Availability
1. Access Product Settings
Navigate to Sales → Offers
In the Forms tab, select the offer containing the unavailable product.
Open the Products tab.
Edit the affected product.
2. Check Quantity Settings
In the Quantity section, check whether the Quantity option is enabled.
How to Make the Product Available Again
If product quantity is enabled, you have two ways to restore availability:
Option 1: Disable Product Quantity
Uncheck the Quantity checkbox.
This allows the product to be purchased without quantity limits (unlimited availability).
Option 2: Set a New Available Quantity
Enter a new value for the available quantity.
The product will remain available until the new stock is depleted.
After applying your changes, scroll down to the bottom of the page and click Confirm to save.
Important Notes
If quantity is enabled but no specific stock quantity is set, customers will still be able to select a quantity at checkout — within the configured minimum and maximum purchase limits.
If the available quantity reaches zero, the product will automatically appear as unavailable again.