Steps to reproduce:

https://en.wikisource.org/w/index.php?title=Index:International_Library_of_Technology_-_Volume_1B.djvu&action=edit

Enable "experimental" visual mode

Select scan 19 (indicated as 13 currently)

Select "Page Number Type:" Number
Select "Page numbering starts from:" 1

Click "Update pagelist" and then "Insert Changes"

Expected result :
Insertion of 19="1"' into <pages> tag, at the appropriate location.

Actual result:
No change to pagelist or <pages> tag

(Aside: It would be nice if the visual mode when inserting changes 'sorted' the entries in the pages tag so that they run in consecutive ascending order.)