Speedtree assets in archvis

Hi there. I have a speedtree for UE asset imported into the free lightroom project.

The asset has a good second set of UV’s for lightmass, and is set to static, but it doesn’t bake. All other objects do. Lighting consists of a directional and many spotlights, most set to static

I can’t find any obvious settings to change. Any hints?

Thanks a bunch