Hey ue24acct-
Thanks for your patience and helping me track this down. The bug exists in the Z Render order on meshes which wrap around each other, Convex Meshes. When opacity is 1, the mesh will want to render the back faces as the front faces along the overlapping convex curve. From your earlier pictures you can see that the Opacity=1 Translucent Cube is rendered correctly Opaque (notwithstanding seeing the Grid lines through it which is a known editor bug and not involved with the scene render itself.) You should disregard my earlier statement about the Disable Separate Translucency, I was thinking the issue lied in a different direction. I have entered the bug report and will keep you up to date as I know more.
Thank You
Eric Ketchum