See Comments.
User reported planar reflections aren't being applied to translucent materials on Mac OpenGL, which may also affect Linux OpenGL and Mac Metal. Need to investigate what this feature requires (i.e. is it disabled because of OpenGL < 4.3) or what bugs are preventing it from working.
Repro Information:
I had to go and find a translucent material in QAGame & then set the Screen Space Reflections flag in the material editor. I forgot to document the exact material, but any translucent material would likely suffice.
Head over to the existing Questions & Answers thread and let us know what's up.