I'm very new to Blender. I had wanted to learn it some day and my young daughter has decided to make a TV show, so I guess that time is now.
I'm using version 2.91 and working in 2D. The rainbow is a Grease Pencil object and the cats are imported images. In this scene, the rainbow is supposed to disappear, leaving the cats to fall down to the ground. I finally managed to work out how to assign opacity values to different keyframes, but instead of fading to transparency, they fade to white and I can't work out why. What am I doing wrong?