Re: [Cin] oops apparently 'subtract' mode is broken!

I think this is a complicated problem. You can see from the Compositor image you posted that the upper track (green) does not totally cover the lower track (red). So sometimes transparency works and sometimes it doesn't. It works exactly the same for me as it does for you. If you try some other overlays you can see that sometimes the result indicates that white values are also used during the blend, sometimes not. PS: I tried using the first appimage created, August 2020, and the same transparency display problem occurs. PS2: I tried rendering a single frame and the result is correct: instead of white parts there is transparency. I did a new rendering applying "subtract" and the result is completely wrong: all black! See images.