My wife's iphone has never successfully completed a backup to icloud- she has had the phone for like 6 weeks now. Its on wifi and plugged into the charger every night, and she has 140GB free in icloud storage. When I manually start a backup in her phone, it just sits there forever calculating how much time it is going to take to backup. Looking in the icloud account, there is like 42GB of space taken up from 2 different backups, but both of those backups are "Incomplete". I can't find any other diagnostic information about why the backups are failing. The backups on my phone work fine.

Apple support chat is still giving me the idiot answers, asking if the screen is locked or not and crap like that.