Oh. Well in that case, it may be how Roblox loads the RAP.
(but also double check that you’re grabbing the right element):
It looks to me that when you open an item’s page, it has a split second of loading for the RAP. It looks like it first sends you the page, then the client is requesting more info from the server to load the page dynamically. This probably saves a bit of loading time for the client as it appears the page has loaded.
What this means for us is that the page loads, THEN the RAP loads on the page. So, the initial GET request won’t return the RAP.
So, you can look through the HTTP Requests in Inspect Element to see what requests your browser made to Roblox to populate the page you needed. And it took me a minute, but after searching through the requests that my browser made, I found the link Roblox uses to get RAP:
It returns a JSON Object with all the data you need.
That’s for https://www.roblox.com/catalog/2409285794/Playful-Vampire. So, it looks like you can grab it from there! I tested it in browser and it seemed to work.