There are several Yahoo issues rises while using it on iPhone. The common problem is Yahoo is not working with iPhone or iOS. Mostly, the issue is with incorrect account settings or wrong account information that is not letting you work with Yahoo mail on the iPhone. So, below are the actions to take to fix it:
1. The first step is to check if there is an issue with your Yahoo account or something else. To fix Yahoo issues with iPhone, check if the account is working out of the Yahoo mail app.
2. Ensure you are employing the latest version of iOS software on your iPhone device.