Thanks for the quick reply.
For my own project: no Build action was set to "Page", all the xaml files have the build action set to "Content" and no System.* reference is added. So this is not the root cause.
For your sample showcase project: most xaml files are set to "Page" instead of "Content". I haven't changed them as there are quite a lot and referring to my own project, I don't think this will fix it.
See attached screenshots from the project file.
- sc from test project.PNG (31.6 KiB) Viewed 854 times
- sc from sample showcase.PNG (24.23 KiB) Viewed 854 times