Hello!
I’m sorry about the delay — the release of TSF v5.0 took up my entire schedule.
TSF generates a description from your content. Only from usable content can TSF generate one (in less than a millisecond).
TSF discards a long list of HTML that I deemed unsuitable for the description generator. You can find that list here: https://tsf.fyi/kb/a/65#stripped-html-tags. These are headers, blockquotes, buttons, form fields, code blocks, tables, and videos.
Regarding the page you linked, there’s no content other than the title. And since titles are discarded (it’s a header), TSF won’t find any “usable” content wherefrom to generate a description.
If you go to the previous article, you can find that TSF did generate a description because there is plain text on that page.
I hope this sheds some light on the issue. If you still require assistance, feel free to follow up. Have a lovely weekend!