I have my work AD account stored in Enpass, and I've added multiple URL entries for the different subdomains at my org. When I visited one of these sites on my iPad, the autocomplete suggestion above the keyboard offered to log me in with that account (see screenshot below). However, it failed with an incorrect password every time. Eventually I figured out that another account in Enpass for a different subdomain was taking precedence and being used to fill in the login form. So really there are two bugs here:
Items that match the subdomain exactly should always take precedence over other items with the same domain but different subdomain
When the iOS keyboard offers to autofill credentials from a particular account in Enpass, that account should be the one that's used