At this moment, layers inside the slider group can't contain animations. Those elements are static. If you have a look at the layer panel, you notice that all layers that are part of the Slider Group don't have animation panels.
You can sort layers inside and outside the Slider Group. Simply grab an element in the layer panel and drag it to the top (outside the Slider Group element) or to the bottom (inside the Slider Group element). Depending on where the layer is placed, the animation panels will be enabled or disabled.
We hope the information above solved your question. If there is anything else we can help you with, and you couldn't find it in our help center, don't hesitate to contact us by chat. We are always ready to help you!