Hi, @stefano.menci,
You are correct that both buttons shouldn’t be displayed at the same time! I’ve added this to our list and it should be fixed soon.
As for Chrome becoming unresponsive, the same isn’t happening to me, so it might be due to the volume of previous background tasks in your app. Are you able to clear finished background tasks, or are you not able to load the page at all? And if you are able to, does that solve the issue?