You see the animation *path* over the timeline clip with ctrl v.
You copy keyframes with alt shift c, paste is alt shift v (means overwriting from current playhead/skimmer position!).
Draw mask is a useful tool, but limited in many respects. Not suitable for complex compositions. For tracked subjects, use SliceX/TrackX (plugins). For animated graphics, use Motion, for advanced roto After Effects.
No worries. I also noticed when you keyframe the transform controls on the mask there is no option (that I can see) to change the movement from Ease in, Ease out, or linear. Which you can adjust when using the Transform controls for regular clip movement in the inspector...?
I'm having this same issue, but with thenova generator. trying to make the "life" flicker from 2 to 3.8 rapidly, works if i go through frame by frame but for some reason wont let me copy and paste. It will cut the keyframes but no paste option appearing.