I didn't intend to run my app on a device with another default language yet, but had a friend try it out. Her OS language is Greek. Text in labels which I display via an IValueConverter are blank. Does this have something to do with the alphabet being different? Other labels that have text set directly in XAML appear correctly (normal English/Roman alphabet), the IValueConverters for the bound labels are being used, and an OS language of e.g. Spanish doesn't have the same problem.
For context, I have an IValueConverter that is bound to an enum, which looks up the string from a pipe-separated list in the ConverterParameter.