Fri Jan 24, 2020 12:11 am
My guess is that this is to with having to invert the key. The color page is designed to isolate colors to work on. By selecting a given color, the resulting alpha channel represents the area filled by that color. But with a chroma key, you want the opposite - for the alpha channel to exclude the selected colors. So the key needs to be inverted and my guess is that this is inverting the normally transparent area outside the frame, making it opaque. This gets revealed when you shrink the frame down and it masks your background.
A quick fix is probably to keep your keyed clip full size, then it into a compound clip and resize that instead. A compound clip is a container that has it's own transparency and resize ability, so should act as you expect.
DC
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