Unable to chagne Particle System Material Element.

I am trying to change the Material Element of my Particle System to one where I have changed the color but it does not change. No matter which Material I select or how I select it makes any difference, it doesn’t change.

I want to change the color of a smoke Particle System to be green, to indicate a healing zone for my character. It worked initially but I noticed the fire Particle System used smoke, so my fire smoke turned green. I decided to duplicate the smoke Particle System and the smoke SubUV and use those to preserve the color of regular smoke. It all seemed to go smoothly until I tried to change the Material Element of my new smoke Particle System. Nothing seems to work and I cannot change it from the original SubUV Material Element.

I have been searching the UE Forum and DDG and I cannot find any solution.

In the screenshot you can see the duplicated Particle System Material I want to use called M_healing_smoke_SubUV.