URG refers to a hotel failing to honor a confirmed reservation of any kind - points or paid. There is specific compensation - at a full-service brand, it's a full comp at the hotel they send you to, plus $200, plus 90,000 points.

You're thinking of the 48-hour availability guarantee, which states that a Titanium member should be able to book a room even when the hotel is otherwise sold out.

There are a ton of caveats on the 48-hour guarantee allowing properties to weasel out of it, and in my experience they often do, but the URG should be pretty ironclad - just with different compensation at some of the lower-tier brands.

I've claimed URG one time, the property tried several ways to weasel out of it, and corporate mostly had my back. I didn't get quite the stated comp at the time (which involved Free Night certificates), but I did get points plus about US$800 in gift cards which actually had more value to me at the time.

The property in this case will state, correctly, that they just see a canceled reservation. Not a URG situation. So it's on Marriott corporate to fix that first. At some point, if the URG actually took place, the property and corporate could argue about who really should pay for that.