I wasn't able to pull yahoo mail from the standard mail app after updating to ios12, so I deleted it from my accounts. When I tried to re-add it, I am having issues. I am able to put in my name and password, but the next screen where you select what to sync (contacts, calendar, etc) is grayed out. After about 1-2 minutes it goes back to Add new account. I've done it several times and powered on/off my iphone 6, but it's not showing up. Funny thing is that my inbox is getting messages that the account was added to my iphone (checking from my desktop). I've noticed similar messages from a few years ago, and I think apple had to put out a patch. Anyone else had this happen? I submitted a ticket with apple.