Operating system: Windows 8.1
Graphics card: Geforce 860m
Broken: 2.8 - 2019-04-26
Short description of error
when using a reflection plane, lamps will show up in the reflection in a render, but not in the viewport. to make matters worse, the lamp can actually shine through the corner of an object (meaning it will be visible in the reflection even tho its behind the object.
Exact steps for others to reproduce the error
The attached .blend file has the most basic example setup I could come up with.
The bottom-left has the viewport, set it to rendered mode. Neither lamp is visible.
Hit the render button, the rendered view shows the lamp on the left, and the one behind the cube will be showing through as well.
Here's a comparison image:
and the blend file: