Main category not saved and it breaks the URL structure

We have issues with saving the main category (when more than one are selected) for the posts.
It lets you chose the main category but it doesn’t save it.

Wordpress v6.9
Newspaper v12.7.3

Some AI debugging info:

TagDiv themes (Newspaper/Newsmag) implement their own “Primary Category” logic using td_primary_cat meta.
When WP versions change (especially 6.7+ → 6.8+ / 6.9), the taxonomy metabox structure changed, breaking older JS that TagDiv uses to capture the radio button selection.

Common causes:

1. JavaScript conflict or deprecation
The TagDiv metabox JS that listens for the “Make Term Primary” click fails to run.
WP changed DOM structure inside the metabox.

2. Theme or plugin outdated
Version 12.7.3 of Newspaper is known to have primary category issues with newer WP versions.

3. Autosave overwriting meta
If Gutenberg autosave is active, it can remove td_primary_cat before final save.

4. REST API conflicts
Security plugins or caching layers (Cloudflare, LiteSpeed, WP Rocket) may block the POST request saving meta.

Can I get some help with it?

It started last week. Let me know if you need more info or details.
thx for your fast reply since this is an urgent matter for our website.

Thx for the reply. We use Rank Math SEO.
Will test and get back to you.