I haven't played in a while and wanted to see what was added (props,store,models,ect.) ,I saw that there were new props added and that people we using them but I couldn't see them at all. No "Errors" but I'm not sure was wrong. Props that I couldn't see Picnic Bench,Confessional Booth,Gazebo,Wall Bench,Port-A-Potty,Inflatable Raft,Swan Boat,Refrigerator,Freezer Door, and Dumpster. I hope theirs an easy fix like a texture pack or addon :c Might just be my gmod messing up but I dono. Example Swan Boat:
Try installing CSS textures, if not verify your game content and try reloading all addons on the server, if nothing else works then i'll try find some more solutions for you.
If the issue was something related to the content he would see a huge "ERROR", and the shadow can be seen on the floor. That's just odd.
There are addons that remove errors from displaying. In which case his screenshot is a perfect example. If he isn't, then that is weird since an error should display. You could try verifying your gmod cache. You can also download the content pack. When you join the game, a link can be found in BIG RED letters. You could also find it here. Subscribe to ALL of them. If it still doesn't work, verify gmod again. http://steamcommunity.com/workshop/filedetails/?id=161553629 We do also use CSS textures. I can't see some props/weapons without css installed. We also do use a few tf2 textures too but not many. Installing that too "may" help.