Normally I find booking (and then taking) a restaurant reservation works well, the points normally post within 2 days. This is via the relationship with OpenTable.
https://ihg.iseatz.com/trip-extras/us/en/restaurants

However, I've booked and completed 2 reservations in the past 2 weeks and neither have had the points post. Is this dead?

Or, is it a dodgy site and I should actually be booking via https://www.ihg.com/trip-extras/gb/en/restaurants ?