Thanks for reaching out to us here in the answers forum! I'm sorry you are experiencing this issue with your guide within SlingPlayer for iPhone. Since the issue is only occurring on this one device and you are getting your channels when viewing the guide on your PC, I would advise uninstalling and reinstalling the application on your iPhone.
Here is an article from our support site which should assist you with this:
Hope this helps!
The Sling Moderation Team