Hi Graham,
I have checked your site assigned to this Themeco license, however I could not find the blog page. However on the search results, I see that your blog posts are appearing (see secure note).
Head over to Settings -> General section and make sure that you have correctly setup your Blog page (see posts page in the screenshot below). Also you can set default number of posts to appear on your Blog page (see Blog pages show at most in the screenshot below)
Then head over to Settings -> Permalinks section and regenerate your .htaccess file. You can select the option postname
and save the changes to reset your permalink settings.
If you’re still having issues, I would then suggest you to disable all of your 3rd party plugins except Cornerstone plugin and see if your plugins causing this issue. If the issue is resolved, you can then activate your plugins one by one to see which plugin causing the issue.
Also I see that you have an active child theme. To see whether your issue is related to your child theme customizations, you can disable your child theme temporarily by activating your parent theme and test your issue further.
If you’re still having issues, provide us with your WordPress credentials along with your FTP credentials in a secure note to investigate it further.
Thanks!