Steps to reproduce:

1. Open attached project (wwwTest.zip)
2. Play the 'Test' scene in the editor
3. Click the button, notice the upper text (WWW.error) changes to the error message text (this case: 404 Not Found) and the text in the bottom (WWW.text) changes to the response body text
4. Build and run on iOS device
5. Click the button
6. Notice the WWW.error value is there, but it differs from the one in editor AND the WWW.text returns an empty string

Reproduced with: 5.3.0f4
Not reproducible with: 5.2.4f1, 5.4.0a6