Duplicator: Failed to make prop_physics

Every time I try pasting with either the duplicator or the advanced duplicator I get this error:

Paste Error: [@lua\includes\modules\duplicator.lua:95] bad argument #1 to ‘SetAngle’ (Angle expected, got nil)

The prop spawns at the map’s origin and isn’t in the undo buffer. Help is greatly appreciated, because I really need the duplicator working right now.