我按照上一个Google教程在一个新项目中介绍了Compose/ViewModel/State，但是我遇到了一个我不理解的问题。当我使用Viewmodel中的一个方法将一个对象从null更新为新示例时，UI会被更新，但是当我使用相同的方法只更新这个对象的一个参数时，修改是不可见的。
这里是代码ViewModel

data class AppOscarUiState(
val selectedStep: Step? = null
)

class AppViewModel() : ViewModel(){
  private val _uiState = MutableStateFlow(AppUiState())
  val uiState: StateFlow<AppUiState> = _uiState.asStateFlow()

  fun updateSelectedStep(newStep: step){
    _uiState.update { currentState ->
        currentState.copy(selectedStep = newStep)
    }
  // also tried _uiState.value = _uiState.value.copy(selectedStep = newStep)

  }
}

在可组合的

fun CardDetail(
    appViewModel: AppViewModel
) {
    val appUiState by appViewModel.uiState.collectAsState()

   Column(
        Modifier
            .fillMaxSize()
            .padding(horizontal = 16.dp, vertical = 8.dp),
    ) {
    Text(
                    text = appUiState.selectedStep!!.status,
                )
    OutlinedButton(
                    onClick = {
                        selectedStep!!.status = 16
                        appViewModel.updateSelectedStep(selectedStep)
                    },
                ) {
                    Text(
                        stringResource(R.string.it_starts),
                    )
                }
    }

When the step is selected from a list, ```updateSelectedStep(newStep)``` from the viewmodel is called and a detail container is filled. And when I want to change a parameter, the same is done. A log in ```updateSelectedStep(newStep)``` indicates that the new value is well transmetted, and when the step is deselected and selected again, the new data is visible.
Step is a data class.

So why the modification is not instantaneous ? I have a similar method to update a boolean (not an object) which works fine.

Thanks for your help