For some reason, either due to my graphics card dying or some hammer-related nightmare, the mirror in the starting room acts as a nodraw until I get close to it.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2877016770
Additionally, the small statue at the start looks to have had some polygons culled for some insane, probably also hammer related reason.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2877016727

Don't know if this is fixable, or could be fixed by using hammer++ due to the increased floating point precision.