A live map that tracks frontlines of the war in Ukraine was edited to show a fake Russian advance on the city of Myrnohrad on November. The edit coincided with the resolution of a bet on Polymarket, a site where users can bet on anything from basketball games to presidential election and ongoing conflicts.

If Russia captured Myrnohrad by the middle of November, then some gamblers would make money. According to the map that Polymarket relies on, they secured the town just before 10:48 UTC on November 15. The bet resolved and then, mysteriously, the map was edited again and the Russian advance vanished.

To adjudicate the real time exchange of territory in a complicated war, Polymarket uses a map generated by the Institute for the Study of War (ISW), a DC-based think tank that monitors conflict around the globe. The battle around Myrnohrad has dragged on for weeks and Polymarket has run bets on Russia capturing the site since September. News around the pending battle has generated more than $1 million in trading volume for the Polymarket bet “Will Russia capture Myrnohrad.”