Cannot hide Photos that are in seperate folders ? ONLY from the main Iphone Folder ?

I have a number of private folders to do with photography and specific models of camera, recently I decided to try and protect some of my prize photos by hiding them from view and move them to the Hidden folder.

Example using a folder i created called 'Lumix G85'

My problem is that whether i select 1 or multiple photos to hide from this folder, there is simply NO OPTION to HIDE them ..... The standard process to hide a photo only works if the photo is in the MAIN folder ....... NOT from any other folder ? Has anyone else struck this ? My Iphone is IOS 16.3

The HIDE option is simply not on any of the menu's ?