Why is Reverse Frames grayed out?
I'm very new to Animate, so I'm sure I'm missing something fundamental here. But I did a tutorial where we reversed the frames to keep the motion repeating. So I know it's possible to do this somehow.
I've created my first animation on my own. I'm using Motion Tween to move a lot of things. And I want to add a reversed copy of the frames to the end.
But for some reason the "Reverse Frames" option is grayed out from the menu:

What do I have to do to be able to reverse my frames?
