I connected my Tv Tuner to the USB port, "Your TV signal was lost" is all I get

This may be irrelevant, but I have a question about the TV tuner. I understand that you plug the tuner into the XB1 through USB, not HDMI. I have an Xbox 360 hooked up to my XB1 through the HDMI-in port. In order to play 360 games, I have to use the TV app,
and the TV tuner uses the TV app as well in order to work. I also understand that when you plug in the TV tuner, the OneGuide separates the TV tuner channels from the "HDMI content". My question is this: if I have a TV tuner with a coax cable connected through
the XB1's USB port AND an Xbox 360 connected through the XB1'S HDMI-in port (both at the same time), can I switch between my Xbox 360 and my TV tuner when using the TV app? Thanks for the help!

Are you using the cable to connect to the TV Tuner USB or an antenna? If you are still using the cable that you were using when you did have cable that could be the reason why the TV Tuner is not working. So try using the good old rabbit ears (antenna) and
see if it clears the problem.

Is it the offical xbox tv tuner, i have that and it's working perfectly in the back USB port.

Try uninstalling and then installing the tv app while the tuner is in the back port, that might help.

If you want your xbox one to show / snap the tv signal your set-up has to be like this:

(Not mentioning the soundbar for simplicity)

tuner->xbox->tv

In your configuration the xbox does not get in touch with the tv signal at all.

So xbox-tv-magic is not for people with tuners built into TVs (like you and me)

A solution would be to buy a seperate tuner if your are willing to pay for something you already have...

I'm having a similar problem.

I have a USB TV tuner setup, but I have it disconnected (have done for ages - no USB slots left), but my Foxtel Cable service was working fine.

Then all of a sudden last night as I was watching my cable service all I saw was "TV tuner not found. We are unable to detect your TV tuner. Make sure your TV tuner is connected to your Xbox, and try again."

I slid to the left to open OneGuide and selected HDMI at the bottom of the list but once I selected it it disappears and all I get is the above message on the screen. I am resetting my whole entertainment system settings again but while HDMI is set in TV
Setup (to test commands to the box), cable shows in the TV example on this screen. So HDMI is definitely working but not while trying to open OneGuide.

Not sure how to fix this, but I'll give Carlos Yo's suggestion below a shot to see if that works.