When using offer codes, the offer is no longer able to be redeemed through its underlying id. That is, either an offer is global (and anyone with its id can claim it subject to timing and redemption limits), or an offer can be redeemed via single-use codes.

As soon as one code is generated for an offer, the require_code flag on the offer will be set to true and its id disallowed for redemption.

Further, if you generate codes for an offer, the max_redemptions attribute will be ignored. The offer's timing attributes (e.g., starts_at and ends_at) will still be considered, as will the code's enabled attribute, but a valid code for an active offer will work in a redemption flow, no matter the value set for max_redemptions.