One oddity on Kobo is that many of the Jack Reacher ebooks on Kobo do not have the series index showing on the page. For instance, Kobo shows Persuader (
https://www.kobo.com/ca/en/ebook/persuader as being available but does mention it as being book 7 in the series.
I ended up using the
https://www.jackreacher.com/us/books/ which I take as being authoritative for the series order.