I’ve noticed this after the Porsche update but if I remember correctly this was an issue prior the Porsche Expansion as well. Cars that have active aero on them do not move them during Showcase events. It can be seen most recently in the Porsche Showcases where active aero cars are used (the Carrera GT for example, or the 918 Hybrid). Active aero is working during normal races but not during Showcases.