I've observed the same issue with PgUp/Dn skipping cities in 1.12.

For the list of cities in the Kingdom Report, each type of settlement is ordered alphabetically by default, but it switches between ascending (A-Z) and descending (Z-A) each time you open the screen.  This is, presumably, a bug.  The initial sort should either always be the same (alphabetical ascending) or it should remember how it was sorted the last time the screen was closed and still be sorted the same way when re-opened.

Also, if you click within the body of the table (any column except the first or last columns), it will re-sort on the column clicked.  IMO, it should only re-sort when you click the column headers, not within the table body.  Until I worked this out, it caused me quite a bit of frustration when trying to get to an idle city by double-clicking it in the Kingdom Report, but ending up somewhere completely different because the first click of the double-click changed the sort order of the table, then the second zoomed me to the new city under the cursor.