Google Leaderboard not working

Hi
We are working on one android base game its mostly like subway surfer where the main character have to collect some items according to that the score will generate. Now our game is on final stage the scores are generating, high score also generate our game save in internal storage. Now we want to add google leaderboard in this game. all the necessary things are done by us on google console (ie oAuth ID, Leaderboard name, App ID). We incorporate the leaderboard Name & Key in unreal Engine project settings. When we generate the build and install in mobile the Google Plays tore logging is done. We gave a leaderboard button on home screen when we press the leaderboard button before start to play the leaderboard is showing. when we go back to our game and start to play once game over we try to access the leaderboard with that button it won’t display leaderboard and also the game closed.
Can anyone pls help me out regarding the blueprint or any other issue regarding to this.