New drawing layers cannot go behind 3d objects

I have a 3D environment in a scene, and I have 1 drawing that behaves normally but when I create a drawing layer and move it into place, I can’t get the drawing to go behind 3D objects, no matter where i move it in 3D space. I have 3D enabled on the layer, and can move it with the 3D animation tools. Even when I duplicate the existing layer that works, the duplicate appears in front of everything. I’ve made all of this work before, but is it possible that my 3D background is too complex? I’m on harmony 12, with an FBX background in Windows 7.