This bug is a bit hard to reproduce without setting up an entire new site with API access, because I can’t try it out on my client’s live site.
The site has a collection list that only lists the latest press release, from a collection of multiple press releases. The collection list in question is limited to 1 item and sorted Newest to Oldest. When publishing to the collection via the API, the collection list on the homepage (the left box all the way on the bottom of the page) does not show the latest collection item. However, when going to IR->Press Releases, where all items from the same collection are displayed, it sits there at the top.
The only way to make the collection list on the first page to update is to make a dummy change to some part of the site and then publish it.
Here is my site Read-Only link