[NTG-context] Font encoding: \uppercased

Greetings all, Taco mentioned the command \uppercased{to get all uppercase letters}, and it works just fine…until I try to use my self-installed fonts. The quirks come up with diacritics, and this leads me to believe that there is an [encoding] or [regime] issue here, as I had similar issues earlier with the font in general. For example, with \uppercased{Krübel} I receive: KRüBEL. Do I need to "make a statement of my intent" in a typescript file or somewhere else to resolve this? Kind regards, David