Async giving me problems.

I know that async functions are great because they don't block your UI thread, so the app can continue running while some long process is running.
Here's the problem my data repositories are all async. So I have functions like

public async Task<ObservableCollection<Categories>> GetItems()
{
    CreateConnection();
    return new ObservableCollection<Categories>(await connection.Table<Categories>().ToListAsync());
}

I then use the code like this

//List of categories
public ObservableCollection<Cagegories> ocCategories;
//List of categories
public ObservableCollection<Products> ocProducts;

//build an accessor for the repo
public CategoriesRepository CategoryRepo => new CategoriesRepository();
public ProductsRepository ProductRepo => new ProductsRepository ();

//Constuctor for page
public ShowCategoryTable()
{
    LoadTableData();

    //combo box of categories
    cbCategories.DataSource = ocCategories;
    dtProducts.DataSource = ocProcucts;
}   

public async void LoadTableData()
{
    ocCategories = await CategoryRepo.GetItems();
    ocProducts = await ProductRepo.GetItems();
}

When this code is called, it spawns off on another thread, as it should.
Here's the rub, the code that uses the result is executed before this call is finished, which will in turn cause a NullException to be thrown, because the thread that is getting the data still has not returned yet.
I was under the impression that this is what the await call was for. That this would in effect make an async function become synchronous (but using a backing thread for the process).

I've already tried this too.

//Constuctor for page
public ShowCategoryTable()
{
    Initialize();
    ConsumeData();

}   

public async void Initialize()
{
    await LoadTableData(); // I've tried even using ConfigureAwait for this and still had the same results.
}

public void ConsumeData()
{
    //combo box of categories
    cbCategories.DataSource = ocCategories;
    dtProducts.DataSource = ocProcucts;
}

When this runs it reaches the await it starts that thread, and immediately attempts to use the data, even when I have tried breaking it into separate async functions and calling them independently

I have tried the code with both ConfigureAwait and even using true and false. But no matter what I do, it seems that my thread is not waiting for the data to return. I can write some really unpleasant code and use Task.Wait(xxx) and make it wait 200ms or so. But that is really bad coding in my experience, and should be avoided like the plague.

The hard part becomes, how can I make these async DB calls execute and return before the UI consumes the data? effectively, how can I make async DB functions perform synchronously?

From what I've read it sounds like that's what await is supposed to do, but it's failing to do so for me.