Have you tried a different monitor/TV to see if it does the same thing with a different screen?
The Intel vs. nVidia device usage shouldn't matter much. There should be an option somewhere you can disable the Intel and run only the nVidia card, but it'd drain your battery in a hurry when you go unplugged.
I've had issues with new Dell's that had problems outputting video through the displayport on the external usb-c dock before. Solution was a BIOS update off Dell's support site.
Is your monitor connected through a dock or are you plugging directly into the laptop? I can't even begin to tell you how many usb ports the wife and boys have broken and cracked on mine over the years. HDMI should be a fairly snug connection, with almost no play. Possible too if you disconnect this monitor frequently that you're wearing the pins out on the computer. I know you tried a new cable, but certain connectors are only rated for so many insertion cycles.
The Intel vs. nVidia device usage shouldn't matter much. There should be an option somewhere you can disable the Intel and run only the nVidia card, but it'd drain your battery in a hurry when you go unplugged.
I've had issues with new Dell's that had problems outputting video through the displayport on the external usb-c dock before. Solution was a BIOS update off Dell's support site.
Is your monitor connected through a dock or are you plugging directly into the laptop? I can't even begin to tell you how many usb ports the wife and boys have broken and cracked on mine over the years. HDMI should be a fairly snug connection, with almost no play. Possible too if you disconnect this monitor frequently that you're wearing the pins out on the computer. I know you tried a new cable, but certain connectors are only rated for so many insertion cycles.