Last on Page running header not working -- except on last page

[SJRiegel]

A co-worker is using Running Headers to generate a First and Last number heading on each page for an index. The running headers should be picking up a character style that is set as a nested style in the paragraph style. I took the file to my machine, and am having the same issue.

 I have used this scheme before, and it used to work perfectly, but now the Last on Page variable is returning no result. First on Page works fine, but last will not, except on the final page of the index, where it works as expected. I can send a link to the InDesign file is anyone can take a look.

OS is Mac Big Sur 11.4 and InDesign version is 16.2.1

[Mike Witherell]

Send a link and we will double-check it for you.

[SJRiegel]

Dropbox link to file

thank you for having a look.  

I tried using the BreakTextThread script on a copy of the file to see if unlinking the text frames would help, but that made its own problem. After running that script, all of the pages showed the last number from the first page. I was only able to get the correct number on each page by going in after the script and using Cut and Paste in Place for the text frames on each spread.