Multiple record update only works once

Hi Ray, I have a paginated results page (200 per page) for a table that contains over 70,000 entries. My client has just tried to update all entries for a particular user by first searching for the entries, which displayed 311 results over 2 pages, then he used the select multiple checkbox on the first page of results to select them all, but when he tried to update them, they didn't update. He then tried the same thing on page 2 of the results and that did work.

I therefore thought that the issue may be with the pagination so I changed the page to display 500 results at a time so I can now see all 311 results. However when I select multiple records (either all or just a few), they aren't updating.

I tried adding a few test rows and was also able to update them successfully - the issue seems to only be happening with multi-page results.

Could you take a look for me? I've attached the page and have included further access details in the PM.