Dedicated server throwing SOLID_VPHYSICS error

I’m trying to run a dedicated server of TTT. I’ve been having problems in the past so it’s a basic server with no addons and only ttt_67thway_v3 running terrortown game mode. I have also mounted cstrike in the mount.cfg. This removed most of the VPHYSICS errors, but three still remain:

SOLID_VPHYSICS static prop with no vphysics model! (models/props_buildings/buildingskybox_002a.mdl)
SOLID_VPHYSICS static prop with no vphysics model! (models/props_foliage/tree_deciduous_card_01_skybox.mdl)
SOLID_VPHYSICS static prop with no vphysics model! (models/props_foliage/cattails.mdl)

I assume, therefore, that these are not cstrike files and I need to find what I need to mount for this to work or whether I need to add these files manually to my server.