In Poser, RBM works brilliantly, except that the reflections are simply shifted copies of the original geometry rather than a flipped version as would happen with a mirror. Is there any way to change this behavior?

Additionally, the SSGI does a similar thing, where an object with high brightness on the left side of another object will cast its light on the right side of the illuminated object (and vice-versa).

4.2's RBM doesn't work well in Poser, and the MXAO just makes everything dark no matter what settings I use, so I use 2.0.3f1, as it gives much better results.

phexitol wrote: It probably behaves like this becouse of wrong depth settings. You can solve this by playing with global preprocessor definitions. Likely, the indicted setting is: RESHADE_DEPTH_INPUT_IS_REVERSED, so change its parameter and reload.
It should fix RBM issues as well. If you're still not satisfied with its reflective properties I suggest you to try the new
Screen-space Reflections shader by MartyMcFly, wich you can download it here.

RBM stands for reflective bump mapping, which by design is no actual reflection, just a glossy effect that is somewhat colored how the actual reflection would be, yet it's very approximate. Screen space reflections, what Duran.te mentioned, are what you look for if you seek actual reflections (mind you, it will put reflections on everything, just like RBM). You should really check the depth buffer settings, with some update, crosire changed the default depth buffer settings. 99% of occasions where old shaders outperform new ones is because the depth buffer settings are wrong.

Duran.te wrote: I've tried various combinations of the preprocessor definitions, and I'm sure it's a Poser problem, but I can't change Poser's code, of course. At some point I'll get fed up enough to just get more comfortable in Blender, since 2.8's Eevee viewport is so much better. I'm just more comfortable using Poser's UI.