impressive
grass seem a little dark.
maybe mix a little yellow and white.

don't remodel... i think it is blender bug.
here is how you can fix.

creat a new cube. select the mesh that has weird result..

and join that mesh to a new cube. (CTRL + J)

and boom your weird mesh become brand new.

how to increase mesh emitter energy.
this is what i get with one mesh emitter lamb object