I have actually run into a similar problem before. I had an entire week not scheduled for me, and thinking it was weird, I checked Kronos, the online site, and the printed schedule. And of course, I had nothing scheduled for a week. I hadn’t scheduled any time off either, but given that school finals were coming up for me, I thought my LOD was gifting me a week off (as she sometimes does). Friday that week, I check my schedule to find out when I work the following week, but something was different. Apparently my schedule changed on me and I ended up missing 2 shifts during the week. Funnily enough, I was shopping at Target during one of the shifts I “missed” and my TL didn’t say a thing to me about my shift. I found out my HR put out my schedule before it was made, which ended up not saying that I was scheduled. In your case, the HR probably messed up the initial schedule and changed it back to the original after a few days.