when im in champion select sometimes it turns black. i think this is a [game play] issue

this only happened to me once but when i went into champion select i saw the main champion select screen but for a split second then it turned all black and i got a ban timer for not choosing a champion. this happened many times, when i am looking at a champion in the previous champion select and someone dodges the next game that i enter the champions abilities are covering the chat so i cant call my lane in time.