Let me preface: I don't know if this is (1) a problem with JS, (2) a problem with Chrome, or (3) a problem with the website.
Sometimes when I click and drag a player card, the focus is not ended when the mouse click ends. This means that the player card gets dragged all around the screen with the cursor until you click on the card again. At this point, you cannot close the player card. The only thing you can do is refresh the page to get the player card to go away.