[Ron Bolte]

I beat my head against the wall for a while on this one too.

The issue is, you have color corrected the clip you are applying the “effect” to. FCX “stacks” the corrector so that it acts on the clip after the “effect” is applied, therefore, any changes to your clip also affect your corner bug. There doesn’t seem to be a way to change the order.
My workaround was to make the clip a compound, step into it and color correct there, then only apply my graphic effect to the compound on the timeline. Hope this helps!