Where are the opacity key frames for masks? When animating a mask's opacity, you cannot find the keyframes in the dopesheet. Is in another place instead?

I've found this bug report but it's not clear if is there a solution or if it's even a bug.
While the bug is fixed (if it ever does), you can use a math node set to multiply to control the opacity of the mask. Animate the values from 1 (full opacity) to 0 (no opacity). Those keyframes will show up on the graph editor or the dopesheet.



Animating the values