I got the same problem. My situation is the code works fine on Mac and iPhone, no setting to nil on the background, but the problem occurs occasionally on the iPad (not every time, 1/3 I guess).

I "fix" this by the save the selection to a temp variable onChange of the @Environment(.scenePhase) .onChange(of: scenePhase) { phase in             if phase == .background{                 tempSelectedId = selectedId             } else {                 if phase == .inactive && selectedId == nil{                     selectedId = tempSelectedId                     print("Restore - scenePhase")                 }             }         }