WpfAnimatedGif: ImageBehavior.AnimatedSource does not exist

I've tried to use WpfAnimatedGif in a new WPF project
https://github.com/XamlAnimatedGif/WpfAnimatedGif

But get the error message
error MC3072: The property 'ImageBehavior.AnimatedSource' does not exist in XML namespace 'http://wpfanimatedgif.codeplex.com'.

Proposed solutions from

• https://github.com/XamlAnimatedGif/WpfAnimatedGif/issues/19 and
• https://github.com/XamlAnimatedGif/WpfAnimatedGif/issues/77

don't seem to help:

I have installed the package from Nuget (tried versions 2.2.0, 1.2.3 and 1.1.10), and git.exe is in my global path. The project is inside a local git repo.

Anyone having any idea what the root cause could be?

MainWindow.xaml:

<Window x:Class="GifWpfTest.MainWindow"
        xmlns=http://schemas.microsoft.com/winfx/2006/xaml/presentation
        xmlns:d=http://schemas.microsoft.com/expression/blend/2008
        xmlns:x=http://schemas.microsoft.com/winfx/2006/xaml
        xmlns:mc=http://schemas.openxmlformats.org/markup-compatibility/2006
        xmlns:gif=http://wpfanimatedgif.codeplex.com
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image gif:ImageBehavior.AnimatedSource="gif.gif" />
    </Grid>
</Window>

Csproj file:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net6.0-windows7.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UseWPF>true</UseWPF>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="XamlAnimatedGif" Version="2.2.0" />
  </ItemGroup>

  <ItemGroup>
    <None Update="gif.gif">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>

</Project>

Try this markup that should be compatible with the newer XamlAnimatedGif package, which is a complete rewrite of the older WpfAnimatedGif project:

<Window x: Class="GifWpfTest.MainWindow"
        xmlns=http://schemas.microsoft.com/winfx/2006/xaml/presentation
        xmlns: d=http://schemas.microsoft.com/expression/blend/2008
        xmlns: x=http://schemas.microsoft.com/winfx/2006/xaml
        xmlns: mc=http://schemas.openxmlformats.org/markup-compatibility/2006
        xmlns: gif="https://github.com/XamlAnimatedGif/XamlAnimatedGif"
        mc: Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image gif: AnimationBehavior.SourceUri="Images/loading.gif" />
    </Grid>
</Window>

See the docs for more information.