Hi @SimonBaur ,
The latest version of ApolloX has this issue with the Avalonia GTK templates fixed on the Colibri iMX8X, so new projects should work out-of-the-box. More details about the problem can be found in this thread: Issue with ApolloX extension and Avalonia GTK MVVM example
See if this works for you.
Best regards,
Lucas Akira