I found this closed issue that suggested that "Source uses /page/2 as the archive page to list all posts" however that page only shows up to 24 posts and doesn't offer a browse button to page 3. My site has now exceeded 24 posts and those posts are no longer visible on page 2. If I manually edit the url to browse to page 3 the missing posts appear. So it seems the theme does support viewing these posts, it's just missing some navigation on the archive page.

Are there any plans to support paging on the archive page? I've already settled in to using Source as my theme with some css customizations and I don't really want to change to another theme. Also I feel like the default first party theme should be fully functional for viewing all posts out of the box.