Static Mesh Editor renders meshes dark

Hi,
I just bought a back from the marketplace (Modular Building Set in Environments - UE Marketplace) which is a fine pack but I noticed when I open the meshes in the static mesh editor that the models are really dark when the editor is set to “lit” mode. Basically the meshes aren’t really dark it’s more like something with the lighting is wrong.
I never had that before, everything looked fine in the editor so far, this is the first time I’m having problems.
Is there anything I can do to adjust the lighting in the editor?

Thanks

Hello, I hope you allready found your awnser but if not Unreal Engine 4.13 - Tutorial - Create Mesh in Engine P1 - Straight road - YouTube maby this will help, Video 3

Greetz