So this just happened and really ticked me off. I was adding a post to a topic I had made, and when I went to post it, it showed as me having logged off and needing to log back in. Can't even go back to copy that thing, not that it would have worked since I'm using a tablet. I just spent 20 minutes typing up a freaking essay, and it's gone. I spent that whole 20 minutes typing. No breaks, no opening other sites, no changing tabs. Just straight tapping away. I don't see any good reason for it to have logged me out like that. My screen never even timed out or anything. Now, I'm probably going to procrastinate a few days and it end up being not near the quality of the original.

HEE has a time limit to inactivity. If you do not have another tab open and are being active on that tab while also typing on the tab with the forum, it will log you out. Typing does not register as you being active since, technically, the page is inactive until you hit submit.

Therefore, this is not a bug, rather HEE's security measures to log people out in case they forgot to. :)