I have had a Slingbox 350 for a few years and recently purchased a 24" Insignia Roku TV from Best Buy. I have AT&T Uverse service. This TV is connected to the DVR and the Slingbox 350.
I am having an issue watching any content on the app (iOS and via computer.) If the television is powered "off", I receive the standard AT&T Uverse "HDMI display error" issue via the screen. I receive audio for whatever channel I'm on. I am able to access the guide and dvr, but am unable to see any content.
If the TV is powered "on" I receive full video and audio through the app. I have swapped 4 different HDMI cables, including 2 brand new ones. As a result of this, I am not able to enjoy my slingbox unless the television is powered "on" all the time.