How do I add a different tag in a tag group to the same expense?

Hello, I'll give an example so this question will be clearer. I have a transaction for Sam's. I bought coffee and scissors. I have a Tag Group named Office Supplies with Tags named "Coffee" and "Stationery." When I add this expense for Sam's with the tag for Coffee, it allows me to add it in the Tag Group "Office Supplies", but it will not give me the option to add another tag to the transaction for "Stationery" under the same Tag Group as "Office Supplies." It will only allow me to add a tag for a completely different tag group. Is this a bug in the system? Thank you for your help.