[fastpages] One built notebook doesn't appear on list of other posts?

I added a notebook called “Following Gravity”, to my fastpages blog, https://github.com/drscotthawley/devblog3/blob/master/_notebooks/2017-02-23-Following-Gravity.ipynb
and the GitHub CI Action log shows that nbdev operates on the file…

converting: _notebooks/2017-02-23-Following-Gravity.ipynb

…with no error messages. It appears to be processed the same as notebooks that get processed.

But when I go to the built site, https://drscotthawley.github.io/devblog3/, all the other posts appear but this one.

Any idea why, or how to fix it?

(If this is a clue: the first date on the list of posts appears twice:

Feb 19, 2020
Feb 19, 2020


That particular file was written 3 years ago, and may have been either corrupted in some subtle way or just out of date from the current formatting nbdev & fastpages require.

What I did to fix this was upload it Colab, and then export a new .ipynb file, and replace the original file in my blog with the new copy.

Now it seems to appear on my list of posts. I say “seems” because of another issue I’ll post about in a separate thread.