Hi there,
Some themes doesn't support or at times there is some kind of conflict that cause this issue. I have fixed this kind of problem with discount / wocommmerce or other plugins issues hundreds of times over the years. I have over 10 years experience of building / fixing websites for clients. Have thousands of happy clients and would like to establish a longterm working relationship with you as well.
Areas of my expertise are PHP, MySQL, Word Press, Shopify, Codeigniter, Laravel, Magento, Angular, Node, JS, Bootstrap, Payment integration.
Looking forward to working with you on this, lets discuss it over chat.
Thanks,
~ Syed