Chosen Solution
I have a 2016 and a 2017 A1708 macbook pro, and a 7 i 1 dongle with hdmi output, on the 2016 when i connect the hdmi cable it shows the picture on the screen instantly, so i know it works but on the 2017 i cant get it to find any screen no matter what i try, same dongle, cable and tv, but no luck at all. Does anyone know why that could be?
What is the macOS versions are they the same? Did you try different ports (Left Vs Right sides)? Also have you tried plugging in Thunderbolt external drive to see if that works.
