I don’t know if all of them are supposed to be dynamic or none but the dynamic head is not displayed correctly. This issue is happening for the Stylish Animation Pack and it’s only for the Idle Animation.
They aren’t dynamic because the thumbnails haven’t been redrawn. You can no longer equip a non dynamic head on R15, so there is no bug here. Just outdated thumbnails.
See the image below; I do not have any head equipped, so it defaults to this. I’m not sure why the MoodAnimation isn’t applying in the Animation thumbnails, though. That is a separate issue in itself and should have a separate thread made for it