How often does it happen with Hyatt that a room will show available on a third party site but not on hyatts website.

I want to extend my stay in Danang and want to book the cheapest room, king room. I'm already staying at the HR for 4 nights ( I had booked a king room and used my DSU) and want to add on another 2 nights. Agoda is showing king rooms available but hyatt.com is showing only ocean view king for much higher.

I'm hoping hyatt website will show the king room soon. If not, what happens if i book a king room with agoda to extend my stay. Will HR make me switch rooms or can I continue in my suite?