Before types can be inferred they have to be loaded by Glass.Mapper. The more recent version of Glass loads types as and when they are requested but this won't work for inferred types. To resolve this you can force Glass to load the types when the application starts.
First find the GlassMapperScCustom class in your solution. You should then update the GlassLoaders method:
public static IConfigurationLoader[] GlassLoaders()
{
var attributes = new AttributeConfigurationLoader("Your assembly name");
return new IConfigurationLoader[] {attributes };
}
Let me know if this doesn't fix it.