Tagging people named witch special firtst character like "Ž" is not possible. If you type "Ž" directly on your keyboard, it enters only "Z" into suggestion textbox, which does not find anyone with name starting with "Ž". You have to go outside the app, copy "Ž" into clipbard and paste it into people tagging suggestion textbox. Then it works. Only pasting from textbox, not writing directly. Suprisingly it works correctly with "ž", but not with capital "Ž". Weird. Simillar for Č, Š and so on.