This is probably an obvious thing I am overlooking but my individual blog post pages (linked from the blog page) show up as just a plain page with only the content of the page. No title, no taxonomy list, no sidebar as it shows up elsewhere. I may have customized a bit too far but I’d like the individual blog post pages to look just as they do in the blog skeleton demo: http://demo.getgrav.org/blog-skeleton/blog/sunshine-in-the-hills
Maybe you’re not extending from the base file, for example like Antimatter does? https://github.com/getgrav/grav-theme-antimatter/blob/develop/templates/item.html.twig#L1
No, that’s not what is happening. I am customizing antimatter and that first line of the item.html.twig file is the same in my file.
Ok, so for anyone else who might be having this issue… found out that I needed to be naming my files item.md rather than default.md. Definitely should be reading the documentation a bit more 
Took me doing a bit of digging in the admin plugin and changing individual posts’ “Page file” and seeing that made the correct changes.