Someone initially posted suggesting using version in the Source string but deleted their post. After replacing every single Source path in the codebase to include the version number (inside the versioned project and outside), it suddenly worked! But why? And does anyone have any cleaner ways of doing this so that the version doesn't have to be updated in hundreds of places when making a new build of the project?
<ResourceDictionary.MergedDictionaries>
<styles:SharedResourceDictionary Source="/Presentation;v1.0.0.0;component/Styles/ColorDefinitions.xaml"/>
<styles:SharedResourceDictionary Source="/Presentation;v1.0.0.0;component/Styles/FontDefinitions.xaml"/>
</ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Presentation;v1.0.0.0;component/Styles/MyStyles.xaml" />