This is a bug. The timeline path seems to have several problems. More on these below.
The earlier date query returns the result you expect, but look at it in the document explorer:
Notice that the entry is a comment and that it has an Owning post.
Now if we look at the whole timeline (filtering out some user cruft), we see:
Just two revision entries for ...
It looks like a bug in the API. It looks like it filters on the creation date of the question, not the timeline events themselves. The question has a timestamp of 1596793060, and using a fromdate of 10 seconds earlier produces the full timeline:
This is probably a variation of this bug and a variation or repeat of this bug that was partially fixed (once upon a time).
Anyway, the timeline does show all your events as can be seen with this query:
where 1563667200 is midnight on July 21st, 2019.
The problem is that ...
This was fixed in the latest deploy.
The bug was basically selecting the wrong date to display (in this case, an associated post), and the right date for filtering and what not. Since not all badges are associated with a post, not all displayed dates were set and when they were set they were off by some (basically random) amount.
I noticed recently that this stopped working and the CSS class short-link needed changing to js-share-link, here's an update:
// @name Stack Exchange: Add Timeline and Revisions links to posts
// @description Adds links to posts to always show history and links to questions to show the Timeline".
// @namespace StackExchange