Amending to add Form 1099 INT

I had already filed my taxes and they were accepted by the IRS. About a week after, I received a form 1099INT of $10 and some change from the IRS. I went ahead and attempted to amend my return to add this form, but now it says I must file by mail. Why must I file by mail if this document does not affect my return at all? 


I attempted to cancel the amend to get advice, but now my turbo tax account says “ready to send by mail”. I’m completely lost.