Premiere Pro :: Cross Dissolve Still Doesn't Fade Properly

Cross dissolve will not fade out clips correctly. It gets down to 10-15% opacity on the last frame and that's the lowest it goes. During playback, you can see how abrupt the fade is.
 
Ticking the "Composite in Linear Color" sometimes improves it, but it's still not a smooth fade. Why is it that I can manually add opacity keyframes to fix this problem (regardless of "comp"), but cross dissolve cannot do a smooth fade?
 
The following are screenshots of the last frame before the clip ends. The cross dissolve is 30 frames long.My system is i5, 560GTX, CUDA enabled, PP CC 7.2.1, Windows 8.1.
 
-White background, last frame, Composite not enabled:
 
-White background, last frame, Composite ENABLED:

With a white background, comp enabled is a bit better, but you can still see the content. I'd expect another frame or two before a complete fade. Black background, last frame, Composite not enabled:

Again, I'd expect another frame or two before total darkness. Oddly enough, after adding and deleting opacity keyframes and switching comp on and off, I managed to get a nice smooth fade with comp OFF with the above example. Some kind of bug? Can't seem to duplicate it yet.Black background, last frame, Composite ENABLED:
 
With the default black background, having comp enabled makes it WORSE. This has been happening since 2011, here's a thread over on the Creative Cow forum talking about the same issue: (and I know there's threads here on the Adobe forum talking about it too)URL....