Use Once Per User Setting for discounts not working

When I add a new coupon code with Invoicing add-on, users cannot redeem vouchers that have the “Use Once Per User” setting enabled. When you try to use the voucher code, the error states that the voucher code has already been used (unlimited uses, use once per user). When I view the invoice generated for this listing and attempt to apply the discount on the invoice, I get the same error.

Uncheking this checkbox in the discount setup, allows a user to use the code and check out with the discount applied, but a user can now use the code multiple times.

Am I missing a setting or is this a known issue? Searching your forums does not yield any answers to this effect.