Thanks for posting to our Forums! I Can see how not getting all the channels you are suppose to be getting is upsetting. Now the first thing I would Check is your configuration, If you are running only HDMI, you could be running into HDCP. You could be having issues with the cable box as well, if you are correctly configured and not having HDCP, to check this you can simply hook the cable box directly to the TV and bypass the Slingbox to see if the issue happens on the TV as well.
Below is an article that will assist you in figuring out if you are running into HDCP, also check out the video attached to the link
Hope this will help!
The Sling Media Moderation Team