Thanks to Hypercast for drawing this to my attention. According to an article on EA’s help page it seems they’re:

…aware of a problem that is causing players on an iPhone, iPad, and/or iPod touch device to be unable to find Android players using emails in the “Find friends in Origin” search field, and are working on fixing it.

All they’re able to suggest for now, though, is the obvious – to try searching for their usernames instead of their emails.

You can read the article and others on EA’s Tapped Out help page by following this link: