Loading (well, reloading) workflows that include Visual Basic expressions in a WCF hosted service is not as straightforward as one might expect. If you have created your XAML workflow based on an ActivityBuilder or a DynamicActivity then the Visual Basic settings aren’t configured automatically.
There may be occasions when you’ll want to save the XAML version of a workflow (root activity) while persisting it. In my case this is normally to ensure that when I persist a workflow and later want to reload it, I’ve got the exact workflow structure I started with. This article discusses how to do just that.