I'm using the Cylindrical Duct from the RC2 library, but the corners don't look like the pretty thumbnail. The spline is a standard Max rectangle with a corner radius of 0. I have also tried to convert the rectangle to a spline and weld the verts, it still produces the same result. I haven't touched the RC setting. It does this in any file. Pipe 1 and Rectangular Duct work fine. Cylindrical Duct is the only problem preset in the Ducting library.
The attached image shows the resulting model and preset I'm referring to.
Max 2012 64bit
Windows 7 64bit