Happens also on my iPad. How do you report bugs?
Thank you for posting in the community about your iPhone not accepting "Not a Match".
Your issue will be forwarded to a specialty team for review and resolution. You may be contacted by that team if they need to gather more information.
With the mobile app, if things are working correctly it is always wise to "refresh" or "reset" the mobile app by deleting it and then reinstalling it.
Please let us know if this corrects your issue.