Randomly Going Idle?

Recently I've been having an issue where while I'm literally in the middle of a conversation, my status switches to "idle" and I start getting push notifications for the chat I'm already viewing. The only fix appears to be manually switching back to "online", but it just happens again a few minutes later. I'm not really sure why this happens, I didn't even know you could go idle on mobile, let alone while actively using the app.