Object will light up with light but refuses to reflect light from emission plane

lightEmissionProblemt.blend (771.2 KB)
So in this file the object will not receive light from this emission plane.
I have "“surface” as emission plane and then I have a image to give character like in world hdr setup. I have a file that this does work on. But on this one as you can see its prejudiced against my emission plane. So far have not witnessed this.

emissionProblem.blend (610.2 KB)
Now in this file I have 2 mysteries. THe plane on the bottom dissapears when I go into render mode. ANd again on a different computer this emission plane will not light up this cube as the regular lamp will. I can not even guess why this object will not receive light would

this is 2.81a

It was because I was in NOT in cycles. SO apparently EvEE does not support emission material?
Still do not know why this bottom plane on the emissionproblem.blend hides when I go into render mode
So when things go wrong in blender I need a diagnostics checklist to go by. There are all these requirements to be in place for things to work.