Hey Alisha
I just tried this url: http://www.investandprotect.com.au/blog
And I do see your list of blog articles (just 1 for now)
Please provide a link example so we can test
Anyways what's really important for SEO is the canonical url, so if you check the source code of pages, even if you access it with the .html url, the canonical url will indicate the url without .html (because of the option you have checked)
And google will index only the canonical url ... and not the one with .html
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