iCloud wont make a backup on new phone - but I have enough storage

Just got the new 12 mini. My iCloud has 50GB (using the .99c plan). My storage is at 31.4GB. Phone wont let me create a new backup. Says "This iPhone cannot be backed up because there is not enough iCloud storage available". I deleted my old phones backup thinking that would help but it hasn't. I've restarted several times, and I have the latest update, but it still wont let me create a backup. How do I fix this?