I've just had a look in the logs and I've found this. Not sure if it's the cause? I've attached the log in case you need to have a look
ERROR: Material::getVar CANT FIND VAR boh for shader Flintwall
ERROR: Material::getVar CANT FIND VAR boh for shader GoodwoodHouse
ERROR: Material::getVar CANT FIND VAR boh for shader NearGround02
ERROR: Material::getVar CANT FIND VAR boh for shader NearGround01
ERROR: Material::getVar CANT FIND VAR boh for shader Ground02
ERROR: Material::getVar CANT FIND VAR boh for shader Ground01
ERROR: Material::getVar CANT FIND VAR boh for shader 3D_People
ERROR: Material::getVar CANT FIND VAR boh for shader Flintwall
ERROR: Material::getVar CANT FIND VAR boh for shader GoodwoodHouse
ERROR: Material::getVar CANT FIND VAR boh for shader NearGround02
ERROR: Material::getVar CANT FIND VAR boh for shader NearGround01
ERROR: Material::getVar CANT FIND VAR boh for shader Ground02
ERROR: Material::getVar CANT FIND VAR boh for shader Ground01
ERROR: Material::getVar CANT FIND VAR boh for shader 3D_People