My carpet does the same thing. I actually closed the slides on myself so I could watch what's happening. I used the remote to close the slides. Don't trust the DW not to leave me in there. Because the carpet is warped and no longer lies flat, it gets caught on the edge of the bed instead of sliding under the bed. The rollers are far enough back that they don't come in contact with the slide carpet.
I haven't tried my fix yet, but here is my plan. There is a solid black piece under the carpet that is part of the slide. Not sure if it's a guide or what. The plan is to use carpet tape to tack the carpet down. That should help the slide carpet lay flat enough so that it goes under the bed. If you get a chance to do that before I do, let me know if it works.