A valid discount group should not contain characters like double apostrophe(“) and hyphen(-). And, it should be less than 30 characters. Also, customer tags in the discount group are case sensitive & we don’t recommend using special characters.
You can add a tag according to the discount you want the customer to access. For example, ‘wholesale’, ‘wpd50’ etc. These tags are associated with the discount groups as shown in the image below. You can learn more about customer tags here.