Whilst not directly answering your question, points posting to the IHG Rewards account does seem a bit and miss these days. Whilst when they do actually post is now a much faster process, it does seem that one in every six says requires manual intervention to get any points posted.

Instead of using the Twitter page I would suggest calling the helpline. If it has been over a week since you checked out they are usually very helpful and depending on who you get, tend to resolve the issue there and then whilst on the phone.