Application title bar disappeared - UWP app

Question

I have na uwp app (published in Windows/Microsoft Store), and the app title bar is normally this:

I was doing some tests in my app (to test the fluent design system) and I made some changes and I did not notice, because now it appears like this:

The name of my app has disappeared and the ellipsis (...) that is included in the header of the page also does not appear.

How can I resolve this?

Answer 1

It happened to me too exactly when I was testing fluent design system!

To recreate the issue. Simply Add

// Extend acrylic
extendAcrylicIntoTitleBar(); to OnLaunched at App.xamel.cs

Then add following code to App.xamel.cs

/// Extend acrylic into the title bar. 
private void extendAcrylicIntoTitleBar()
{
CoreApplication.GetCurrentView().TitleBar.ExtendViewIntoTitleBar = true;
ApplicationViewTitleBar titleBar = 
ApplicationView.GetForCurrentView().TitleBar;
titleBar.ButtonBackgroundColor = Colors.Transparent;
titleBar.ButtonInactiveBackgroundColor = Colors.Transparent;
}

Next you need to fix the missing using by hitting Ctrl + . key.

At this point the title bar disappear. Even removing the extendAcrylicIntoTitleBar() function will not solve the issue!

The title bar will appear again if I remove following

using Windows.UI;
using Windows.UI.ViewManagement;
using Windows.ApplicationModel.Core;

I am not sure if it is a issue. That seems to be the way fluent design works

Above test is done according to
https://learn.microsoft.com/en-us/windows/uwp/design/style/acrylic#acrylic-theme-resources

Answer 2

The last value is cached in the registry. Try deleting this:

[HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\SystemAppData\<GUID_PublisherID>\PersistedTitleBarData\<GUID_PublisherID>!App]
"AppVersion"=hex(b):00,00,00,00,00,00,01,00
"ExtendViewIntoTitleBar"=dword:00000001

Also saved nearby is last window position, and splash screen info.

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