I had the same issue. Brand new Samsung QLED 90T and no devices or scenes showed up on the TV. I reset the TV, verified firmware, uninstalled/reinstalled the app on my phone several times, rebooted my hub, etc etc. I got to poking around on the IDE and under the Location section I clicked the link to List my scenes. I received the error, “An error occurred fetching scenes for this location”. Based on that error, I assumed the issue was with my configured scenes. I also read on another post online there issue with showing devices on the tv was scene related as well. Additionally, my experience transitioning to the new app was unbelievably painful. So, I took a chance and deleted the configured scenes on the new Smartthings app and my devices showed up on the TV. Oddly enough, the TV had scenes that I recall deleting some time ago which makes me believe the conversion to the new app was not only painful, it also left some orphaned scenes. I will have to open a ticket to have the old scenes removed however, for now, I at least have devices on the tv and the Ring camera notification actually works. I have quite a few devices, an integration with my security system, heavily integrated with Webcore, have Alexa, Google, IFTTT, Nest and several other services so, I was super reluctant to delete the scenes I had. The link to the other post I referred to above can be found here Smartthings not working on new Samsung TV "no registered scenes and devices"