Using https://search.google.com/test/rich-results I ran a test on this web page: https://www.cwcycles.co.za/product/sram-pc-gx-eagle-chain
However, when I view the source for this page in Chrome there is no such block. Additionally I have inspected the page in the dev tools to see if JS is building it, and I have also changed the UserAgent to be GoogleBot, but still no luck in producing this JSON-LD block.
Why is it that Google's tool is seeing it but I am not?
Note: Originally I discovered this issue in a Python tool I have built, but have replicated it in the browser for ease of asking the question.