P: Detect ‘Monochrome” and ‘black and white’ in cloud-based searching

I am using Lightroom v10.3 9B89DD/197. on iPad (11" M1 Pro iPadOS 18.4.1).

I am trying to find the 'monochrome' or 'black and white' images in my collection and it is only returning a few dozen or so of the hundreds of images I have that are monochrom/black and white--not simple 'desaturate', but properly made using Lightroom's own B&W 'button' under the colour panel.

These images are from various camera models: Nikon D800E, Sony RX-10iii, Olympus/OM System OM-1, for e.g.

To reproduce the issue: In 'All Photos', I begin typing in the search field (magnifying glass at top right) "mono—" and select 'monochrome' from the drop down list. Only a few dozen images show. I clear that search then start typing 'black—' and choose 'black and white' from the drop down list. Again, only a few dozen image show--the same image.

Perhaps I am expecting too much from the Sensei search, but it should be able to recognize monochrome images or, at the very least, choose those images that have been created using the B&W button.

Please address this issue and rectify it.

Thanks.