Tech support got back with me… Seems it’s a bug… Here’s what they told me:
From some original descriptions we’ve tried to reproduce the issue but weren’t able to. In the original test, however, we didn’t note that it was the top face had been flipped around specifically. We went back and found that if the cube effect is done by adding a cube and moving media into it, or by converting the video track into a cube, and switching the H & V of the top face, even in the Red Engine stand-alone, touching a Keyframe will cause an immediate crash, like you saw. Because you’re working in Avid, it brought up an Avid alert window, which made us look into Red working within Avid, but really it’s a problem within the Red interface.
We’ve noticed that not only will that happen in Red but it’s also cross platform (Windows and Mac), and we’ve noted it as a bug. However, via odd coincidence, there is a very simple workaround.
If you first create the cube with the video tracks, and then adjust the Front Face to switch H & V, and then switch the Top Face to H & V, the problem will not occur. Then, simply go back and switch the Front Face from H & V to Never (no flip), so that only the Top Face has the H & V flip, the crash will not occur.
Try it this way and let me know if that doesn’t work. Sorry for taking a little while to find the error, but we’ve since been able to produce the crash, as well as prevent a crash with this workaround, 100% of the time.