Error: Converter failed to convert value of type 'Windows.Foundation.IReference`1<Microsoft.UI.Xaml.GridLength>' to type 'Double';

[snandaworld]

Describe the bug

Started getting the Below error while Debugging WinUI 3 App with MSIX and Self-contained package after upgrading the Windows app SDK to v.1.5.
Error: Converter failed to convert value of type 'Windows.Foundation.IReference`1<Microsoft.UI.Xaml.GridLength>' to type 'Double'; BindingExpression: Path='TemplateSettings.CompactPaneGridLength' DataItem='Microsoft.UI.Xaml.Controls.SplitView'; target element is 'Microsoft.UI.Xaml.Media.Animation.SplineDoubleKeyFrame' (Name='null'); target property is 'Value' (type 'Double').

Steps to reproduce the bug

1. Run any WinUI 3 App with MSIX and Self-contained package in Debug mode and observe the Output window. You will see the error message.

Expected behavior

Prior to WAS 1.5, this error wasn't seen.

Screenshots

NuGet package version

WinUI 3 - Windows App SDK 1.5.0: 1.5.240227000

Windows version

Windows 11 (22H2): Build 22621

Additional context

No response

[parko65]

I started seeing this after upgrading WinUI3 app to SDK 1.5 and .net8. I've rolled back to .net7 and latest 1.4 until I understand what detrimental effect this has.

[ranjeshj]

Looks like a dup of 9384