Itunes won't play .m4a or m4r tones
In iTunes 12.7, the ringtones functionality has changed. You can still copy custom ringtones to your iOS devices using this guide from OSXDaily, or this Apple Support article.

If you still need access to the features in previous versions of iTunes, Apple made iTunes 12.6.3 available for cases like this: Deploy apps in a business environment with iTunes

Check out this Apple Support document for more information on the iTunes 12.7 update: Changes in the new iTunes