Image Imported as plane not reflecting? I've got a simple scene with a Background plane, a glass, and a glossy floor.
For whatever reason, the Background plane doesn't reflect off the glossy floor, as seen here:


Here is my node setups:
There's nothing wrong with the plane, it is reflecting unto your glossy floor, it's the angle of the camera and the fact that the floor is a perfect mirror that is misleading you to think it is just showing through and not reflecting.

To see this, try to change the base color of your glossy shader:



Or, you can change the roughness value of your glossy shader to something above 0, and see that the reflected bits are rough:



Give it a go and let us know if this is truly the case or if something weird is actually happening.