This is happening because you're reloading media every job by using sheets. My S80600, upon loading new media, rolls media out for a couple feet, then back and leaves some media hanging out front.
You can roll the media back using the up arrow button after the above is done. The media needs to be at least even with the glass door/or the cut off slit on the platen - no shorter than that.
I would recommend printing off the roll though, as others have mentioned. That way you only have to deal with this once per roll instead of every job.