So I'm getting this exception:
SetUp : System.NotSupportedException : No data is available for encoding 775.
The documentation tells me https://developer.xamarin.com/api/type/System.Text.Encoding/ that's the code for Baltic, but that's about it. The phone's internal language is English, the Application is in English. There's no reference to anything anything from any of the Baltic languages, except my physical location on the world map.
Moreover, I ticked everything in Build => Linker => Internationalization.
This issue is quite difficult to google as well. Usually refers to random C# build issues, but the app itself builds fine (even without any of the Internationalization options ticked; this is something I did specifically for the UITest build)
Using debug build (and yes, shared runtime is turned off, that was an exception in its own right)
Tried to build .apk-s on different phones (and no, I do not think this matters, just getting desperate)
NUnit reference patch 2.6.3 (upgrading to 3 caused different internal exceptions)
Xamarin.UITest reference patch 1.3.3 (did not work with the default version either)