I used it a good amount last week, no problem. There are various little temporary glitches like that from time to time. Sometimes shutting down the browser and computer and restarting gets things back, or sacrificing a chicken to the IT gods!
I just tested with one of my drafts. I only use buy it now so scheduling is not a thing with me. When I look just below add best offer the options was still a toggle on or off for scheduling. It's possible the toggle just got turned off somewhere along the way.