Coupons not appearing on checkout

Hello,

We have a scenario, where we need to be able to manually change users from a free plan, to a paid plan within the wordpress dashboard. We set the plan start date, and allow 1 year subscription. The issue, is that when the user logs into their profile, they can “Make a Payment” for their 1 year upgraded plan, but when they go to select Stripe, there is no option for a coupon code to be entered. We have valid coupon codes that work for new user registration, but for some reason, non of the coupons are working for existing members, despite having no limitations on the coupon codes. We also enabled coupons on the Plan pages. Any assistance is appreciated.