Firstly, I’m on 2.79b, not 2.8.
What I first thought was an error seems to be a feature, but only applied to the high res models.
I created a particle system on a sphere, then I created another sphere and added the exact same system except I changed it to a medium res model.
When I click on the Optimised Display checkbox, only the High res materials are affected.
Here’s a screenshot to help you better understand what I mean.
I’m just curious if this is only supposed to effect the high res option and nothing else.
If so, then it works fine, if not, then it’s not working.
EDIT: - Yes, I mean the materials. I kept referring to models when I was changing the Materials settings. Apologies.