Either I'm just poopoo brain an couldn't find an answer on google because of my, or they made it so you couldn't use the motion animation tool on a group of layers. Now at first this might not seem that big of a deal, but with things like needing to animate the color an lineart separately seems a bit confusing to me, of course in a project that has such. I thought this small animation tool would be useful for small movement in character or background art for convince of having a program that you can make fully fledged pice of artwork in, with the bonus to make it move a bit. I was originally going to use this for a project that requires animated sprites, since Fresco is my main art tool, and saw this feature as an easy way to animate the things in it right after drawing it.
Again could just be missing something here, but I tried all other options that I could think of and even ran some tests to see that it was infact the groups that was the problem.
You can definitely use the animation tool on a group of layers. You can also use it on separate layers within a group. Either select the group then the animation tool or double tap/click on the group to open it then select the individual layers.
Keep in mind the animation features are still relatively new within the app so they won't have all the features everyone wants straight away.