I am trying to setup a simple trigger. I have an image file as input 7. I want to trigger a fade after a 5 second (5000 millisecond) delay to a video that I have at input 5. I have selected "OnTransitionIn" as the trigger, "Fade" as the function "5-Mission Spotlight" as the input, "500" as the duration, "5000" as the delay.

But when I transition in the image, nothing happens, it just stays on the image. I have tried many different configurations of the above options, including using different images, different inputs, different triggers, but nothing seems to be working.

I have the Max version of vMix.

Yes you`re right or also i cant understand something. Trigger fade doesnt seem to work but if for example we want to overlayin another video,it works ok! I dont understand something me too?
But another way to do this you want is with a simple script as you have max version. You can to go to scripting and put this
sleep 5000
Function=Fade&Input=5&Duration=500&Mix=0
and save it with your desired name
Then you go to your image and you create a trigger-->on transitionin -->scriptstart-->nameofyourscript delay 0 and you`re ok

Create a video with the image using a video program, e.g. 5 seconds

OnCompletion (applies to video, list, photos and powerpoint inputs when they reach the end assuming Loop is not enabled).