I called customer service on this.

(Side note: Typical poor IHG process. I quixotically called the Middle East Diamond support number (+973) since that's where I'm located. After a long hold, a guy answered "reservations." I asked if he could help with rewards. No, he would transfer me. After being on hold for five minutes, the call dropped. So I had to pay to call the U.S. Diamond support number. Automated system: "please tell us the purpose of your call." Me: "Rewards." System: "Please tell us specifically your question about rewards." Me: "Rollover nights." I get transferred to another IVR. "Are you a member of the rewards program?" "Yes." "Please type in your rewards number." "Which property are you calling about? If it's a property outside the U.S., please say the country." At one point it said they sent a one-time password for verification to my registered phone number (I didn't even know I had one). I eventually shorted-circuit this and got to a representative.)

The representative, friendly enough -- and repeatedly effusive in her appreciation of my loyalty -- said that the rollover nights will post by the end of March but she would "double-check." After waiting on hold, she confirmed my number of roll-over nights and said, "rest assured" they'd be posted by the end of March.

(Side note, continued: She said she would transfer me to someone who would give me 500 points as a special gesture for my extraordinary loyalty. OK, great, thanks. I get to a golden-voiced guy. Long-story short, and again thank you much for being so loyal, we wouldn't be the best loyalty program in the world without 100 million guests like you, etc. It's some kind of vacation-club sales effort. I can go to any of twelve fabulous U.S. destinations for four nights at some point over the next year. When I'm there, they will take me on a two-hour tour of the property and presentation of the amenities. All for only $249, which I am to pay now. Don't worry, I can roll it over for six months (ironically) or change the destination any time. And I can get a cash refund after the stay if I want. It was a pretty hard sell. I declined. I did get the 500 points right away at least.)