Bridge fails to search inside subfolders

I'm running Bridge 12.3.3.270 on MacOSMonterey 12.5 and it will not search the subfolders of an external drive - the folders that contain the actual images.

In 'Find' the 'Include All Subfolders' is checked so that's not it.
The dropdown in the top right corner is set to 'Bridge Search: current folder'

I can double click on any folder on the drive and the images appear without a problem. Their keyword data is all there. But If I search by keyword, Bridge returns zero results. It appears it is not reading the contents of those folders.

I've seent this problem covered many times in the Support Community but it seems the same silly solution is offered up - "did you check that 'Include All Subfolders' is checked. 

Any other suggestions?