Simplygon with HLOD problem

Hello guys,
I was testing simplygon with HLOD and I came upon a problem. When I use only HLOD it works (builds), but when I check simplify mesh, the lods won’t build.

Has anyone else came upon this problem?

Oh and by the way, does simplygon with HLOD reduces triangles on entire clusters or I would need to reduce triangles for each single mesh?