Using http://folio-snapshot-stable.aws.indexdata.com/settings/users on March 14, 2018, I was able to enter multiple blank Address Types at Settings->Users->Address Types. At a minimum the Address Type field should be required. This happens in both Chrome and Firefox.
After entering the fifth blank Address Type and saving it, I clicked on Patron Groups and was received the "there are unsaved changes" pop-up. When I went back to Address Types the fifth blank Address Type wasn't there, even though I had saved it. When I clicked on "Keep editing" the Address Type table was present but the Patron Groups table was high-lighted. Strange behavior.