WinUI 3 / MSIX app creates new OneDrive AppFolder (“My App 1”) instead of using existing (“My App”)

I’ve migrated my UWP app to WinUI 3 with MSIX packaging, and also updated Microsoft Graph SDK from 4.x to 5.x. The original UWP app uses OneDrive’s special.AppFolder to store user data, which created a folder named "My App".

However, after migrating, the new WinUI 3 app is creating a new folder called "My App 1", even though:

• The same Azure AD app registration and Client ID is used

• The app is correctly packaged with MSIX

• The correct redirect URI is used:

ms-appx-web://microsoft.aad.brokerplugin/<ClientId>

• Token cache is cleared, sign-in is interactive and fresh

I create the client app instance as follows:

var options = new BrokerOptions(BrokerOptions.OperatingSystems.Windows);

var clientApp = PublicClientApplicationBuilder.Create(_clientId)
    .WithRedirectUri($"ms-appx-web://microsoft.aad.brokerplugin/{_clientId}")
    .WithParentActivityOrWindow(() => hwnd)
    .WithBroker(options)
    .Build();

I have also tried with other redirect uris including:

• .WithDefaultRedirectUri()
• msal<ClientId>://auth

GraphServiceClient.Drives[drive.Id].Special["approot"] always returns the "My App 1" folder.

I need the migrated app to access the original "My App" folder to preserve user data. Can someone clarify:

• What causes OneDrive to associate a new AppFolder despite same Client ID?

• How can I ensure app upgrade does not break access to "My App"?

Appreciate any insight or escalation.