Glad to see the support team is so on top of the messages here...
I have a similar problem but it has nothing to do with the tv being on or off. Mine gives me audio with the blue video signal screen when using cellular data to watch tv. Switch to WIFI and it instantly starts working. Will be following this thread to see if anyone ever chimes in to give us some help.
Hey hls811, I figured it out (no thanks to slingbox support or this community)... I had an HD I cable connection to the TV in which my slingbox was set up to. This was the problem. You have to replace that with the (red/blue/green video and red/white audio) connections or else the signal to smartphones will fail 90% of the time. Don't let these jack A's tell you it'd the 1080p cable output setting. That has absolutely nothing to do with it.
Hope this fixes it for you, brother. Maybe we should start up our own slingbox support team.