Finder sort order not alphabetical (again) I know you might be annoyed by those questions, but here is my specific problem:

A list of PDFs, which is in no explaineable way ordered non-alphabetical. It is consistent between list and column view. Does anyone see the logic behind this or knows a fix?

The naming pattern is Konto_cccccccc_Auszug_20XX_NNN.PDF where cccccccc is the account number, XX is the corresponding year, and NNN is the number of the statement, padded with leading zeros. The visible part is Konto_ccc and XX_NNN.PDF. All statements are from the same account (thus have the same number).

As visible in the image, the last two statements from 2017 are at the top. This happens with no other 10th and 11th statement though. Also 2018_001 is at the top, below the last 2017 statements (wich is correct, relatively).
This was an easy fix... The naming scheme of my bank actually changed, from Konto_cccccccc-Auszug_20XX_NNN.PDF to Konto_cccccccc_Auszug-20XX_NNN.PDF, which is kind of invisible to the human eye. Thanks for @Tetsujin for the recommendation to eliminate typos by copying one name to another!