After installing in WordPress one of the Facebook Instant Articles plugins, the feed can be seen in browser at https://www.example.com/feed/fb/ but the Facebook publishing tool can’t crawl it.
Of course this can be a due to a series of issues, but the ones I came across are:
- URLs in the feed have to match the domain and be absolute, including the canonical links in the content
- Content of https://www.example.com/feed/fb/ should match the one in the regular feed: https://www.example.com/feed/
- The feed shouldn’t have internal redirects, which sometimes WordPress creates