It's weird, I had it recently, but I just saw that I have more "RealView" in the heads-up view. I hope I express myself well. In this heads-up screen, I had several options like show shadow, change perspective, etc. Now I just have the perspective that is active, that's all
On my assembly with a host of different parts, well the realwiew disappears, automatically, because when I make a simple part in a new file, well everything is available again.