January 10, 2018: Microsoft released a .NET v4.7.1 update that is causing WPF-based programs (such as Labeler v7) to crash on font-related issues. Here is Microsoft's webpage with workarounds:

https://support.microsoft.com/en-us/help/4074906/typeinitializationexception-or-fileformatexception-error-in-wpf-apps-t