Issues when saving files to OneDrive on Windows 10 Mobile - onedrive

Question

I’m working on an application where you should be able to open and save files, similar to “Notepad”. It’s a universal application that should work both on computers and mobiles.
The application works fine on computers. It also works fine on mobile if I save or open files locally or on Dropbox.
But if I open a file on OneDrive (via the file picker), and then try to save an exception is thrown: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
If I select “Save as” on OneDrive it works. But every time I select Save after this a new instance of the file is created (I get “file 1”, “file 2”, “file 3” and so on).
I have only tested this on my phone. I might have a bug on my application, but since it works on DropBox I don’t think so. Is this a known issue with OneDrive? Or might I just have some local issues? I’m using Windows 10 Mobile [phone] and OneDrive 17.11.
Here is some code to illustrate the problem:
<Page
x:Class="BasicEditor.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:BasicEditor"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" Margin="40">
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<StackPanel Orientation="Horizontal">
<Button Content="Open"
Click="OpenButton_Click" />
<Button Content="Save"
Click="SaveButton_Click" />
<Button Content="Save as"
Click="SaveAsButton_Click" />
</StackPanel>
<TextBox Grid.Row="1" x:Name="TextEditor"
TextWrapping="Wrap" />
</Grid>
</Page>
using System;
using System.Collections.Generic;
using Windows.Storage;
using Windows.Storage.AccessCache;
using Windows.Storage.Pickers;
using Windows.UI.Popups;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace BasicEditor
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
string MruToken;
private async void OpenButton_Click(object sender, RoutedEventArgs e)
{
FileOpenPicker openPicker = new FileOpenPicker();
openPicker.ViewMode = PickerViewMode.List;
openPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
openPicker.FileTypeFilter.Add(".txt");
StorageFile file = await openPicker.PickSingleFileAsync();
if (file != null)
{
try
{
string fileContent = await FileIO.ReadTextAsync(file);
TextEditor.Text = fileContent;
string token = Windows.Storage.AccessCache.StorageApplicationPermissions.MostRecentlyUsedList.Add(file, "");
MruToken = token;
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write($"Open-Error: {ex.Message}");
var dialog = new MessageDialog($"Open-Error: {ex.Message}");
await dialog.ShowAsync();
}
}
}
private async void SaveButton_Click(object sender, RoutedEventArgs e)
{
try
{
var file = await StorageApplicationPermissions.MostRecentlyUsedList.GetFileAsync(MruToken);
string fileContent = await FileIO.ReadTextAsync(file);
await FileIO.WriteTextAsync(file, TextEditor.Text);
var dialog = new MessageDialog($"Saved successfully");
await dialog.ShowAsync();
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write($"Save-Error: {ex.Message}");
var dialog = new MessageDialog($"Save-Error: {ex.Message}");
await dialog.ShowAsync();
}
}
private async void SaveAsButton_Click(object sender, RoutedEventArgs e)
{
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
savePicker.FileTypeChoices.Add("Plain Text", new List<string>() { ".txt" });
savePicker.SuggestedFileName = "New Document";
StorageFile file = await savePicker.PickSaveFileAsync();
if (file != null)
{
try
{
await FileIO.WriteTextAsync(file, TextEditor.Text);
string token = Windows.Storage.AccessCache.StorageApplicationPermissions.MostRecentlyUsedList.Add(file, "");
MruToken = token;
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write($"SaveAs-Error: {ex.Message}");
var dialog = new MessageDialog($"SaveAs-Error: {ex.Message}");
await dialog.ShowAsync();
}
}
}
}
}
A beta of my app is available here: https://www.microsoft.com/store/apps/9NBLGGH3MFM3
Another app with exactly the behavior when OneDrive is used is NotepadX.