I also use a Sling PRO-HD and this problem still exists for me. No matter what TV you connect to it still sends the 4:3 signal to the TV and is never full screen. Other apps (youtube, netflix) using the Lightning to Digital AV Adapter display in the proper format and fill the screen as expected. C'mon Sling, it's been nearly 6 months since the iPad app has been updated and this is a serious flaw! I travel frequently and have this issue connecting to all brands of TVs at hotels. I expect better support for a $15 app and it is also disappointing that there is no way to contact Sling support without paying a per incident fee, especially when this is a bug in their software!
This has probably been asked a million times but not finding my answer. We have a new iPad Air 2 (OS8.1), and Apple HDMI converter cable coming off the iPad and mirroring enabled on the iPad so what we see on the desktop is what we see on the TV via HDMI cable connections. Only issue I am having is Slingbox output to the TV is not correct. When streaming HD channels they look stretched like they are coming out of the iPad 4:3. I have the aspect ratio in the live TV settings set to auto but changing those settings does not seem to matter or make any differences. Any advice on settings to make the output of the iPad Air 2 aspect ratio look correct on my external HDMI 16:9 TV?