Also, in the packaging options I have selected all locales. When I filter by existing, the list is empty, even though the .locres files exist for all the cultures specified in the Localization Dashboard.
Is there anything else that I need to do in order for my translations to be selectable from the Editor Preferences - General - Region & Language - Preview Game Language?
In order for the translations to appear on the list set Localization Dashboard → Loading Policy to Game and restart the editor.
I incorrectly assumed that Always was the correct setting, as I thought UMG preview is editor and Editor and Game are mutually exclusive in that combo box.
Got same issue. Assumed that “Always” is the safest option. Got punished for assuming common sense. The engine wouldn’t even show languages in Packaging->Advanced->Localizations to Package->Show Localized. Not even the default English. And Get Localized Cultures node wouldn’t work too, while Set Current Culture and Get Current Culture were already working with a localized language. That’s ridiculous.