I have use clone to create new object and update like that:

fun sync(item: LibraryItem) {
    viewModelScope.launch {
        val debugValue = item.userMediaProgress.toUpload
        val updated = apiHandler.updateProgress(item.userMediaProgress)
        if (updated) {
            val newItem = item.copy()
            newItem.userMediaProgress.toUpload = !debugValue
            _item.postValue(newItem)
        }
    }
}

But I dont get changes in UI. When I create new complete object it works. Why?