Mongolia's capital is officially known as Ulaanbaatar. Due to old stylebooks, some media still spell it the wrong and incorrect way, i.e. Ulan Bator.

AP, Bloomberg, Reuters, WSJ, The Economist, Financial Times, BBC, Nikkei Asian Review, NYT, and now SCMP (29 Dec 2020) all spell it correctly now. 

The only non-complying major news outlets that regularly cover Mongolia are now Xinhua, TASS. Do let us know of other instances, with possibly the contact details of the editor in charge.