Thumbnail Grid category filter broken after update (Archive category empty)

[PascalKueppers]

Hi,

I have a strange issue after updating WordPress, plugins and Lay Theme.

I first tested everything 1:1 on my staging/test server.
After updating WordPress, all plugins and Lay Theme, everything worked perfectly there.

Then I performed the exact same updates on the live site.

Since then, one Thumbnail Grid filter no longer works:

“Archive”

When clicking the filter, the URL updates correctly:

#category-project-archive

but no projects are shown.

Important:

The category exists and contains projects
Projects are correctly assigned to the “Archive” category
The Thumbnail Grid itself works
This worked before the updates
The exact same setup still works on the test server

I already tried:

clearing Lay cache
re-saving the Thumbnail Grid
re-saving categories and projects
removing/re-adding category assignments
changing the category slug
different permalink settings
disabling plugins
hard refresh / cache clear
PHP 8.2

I also inspected the frontend and noticed that the “Archive” category seems not to be included in the generated thumbnail category mapping (data-catid), although the projects are assigned correctly in WordPress backend.

Do you have any idea what might have broken after the update or how I can rebuild/fix the category mapping for this Thumbnail Grid?

Website: hartmutnaegele.com

Thank you very much!