Discount code cannot be applied if value is lesser than order total

[RubenTan]

Steps to replicate:

1. create a price rule programmatically, with value at -10
2. create a discount code programmatically linking to it
3. create a checkout programmatically using storefront SDK graphQL mutation "checkoutCreate"
4. apply the discount code programmatically using storefront SDK graphQL mutation "checkoutDiscountCodeApplyV2"
5. follow the url link in the response body

From there, I noticed that the discount code was not automatically applied on the checkout page. My order total is 5, and the discount value is -10. Is this intentional? If so, where is it documented?