enlightening replies here to my OP, thanks.

Now I have done some search myself too and I see the same commented pattern. Some hotels have simply stopped offering 5k, some others have it bookable on ihg.com but no way to book 5k through App, and then there are those who never offered 5k but some 1k or 2k special rates.

It just baffles me then why some 5k properties can be booked both on ihg.com and App, but some other properties not. I frequent few places where I always book 5k rate but I never before tried booking with App and unfortunately now I see that those my favorites properties are unbookable with App 5k. Well not the end of the world, I just book elsewhere to fulfill my App Accelerate task and continue otherwise booking on ihg.com