Primary Category not working/resetting in Post Settings

Hi, after the latest update the “Primary Category” field in the Post Settings area is Resetting to “Auto select a category” each time I open the post inside Wp-Admin for the editing. In short: the module is not saving my choices.

This is also reflecting in the home page: now every new post has the first category shown, ignoring my own choice for the “Primary Category” and so the label shown.

The “Primary Category” I’m talking about is this one.

Example
1) I go online with this post: “Strictly come dancing: what happens tonight on BBC One”. It has categories: “Watch Now”, “BBC”, “TV”, “Live streaming”, etc
2) I’m selecting “BBC” as Primary Category in the Post Settings, because I want that category to be shown under the post title in the homepage (using Block 14)
3) Instead, the Home Page is showing “Watch Now”
4) I go back in Wp-Admin to edit the post and I find that Primary Category is set on “Auto” (while I had selected “BBC”)
5) I select again “BBC” and save the post
6) But it’s not working. Everytime I go back to editing, the field is on “Auto”. It’s not saving.

So, what went wrong? How to resolve?

Ok, I deactivated the plugin Aruba HiSpeed Cache (which is a mandatory install – automatically updated by the hosting provider) and the saving issue has been resolved.

I’m not using a child theme, I’m using the Magazine Pro template