Subfolders in external drive not appearing in Source window on import

[grjas2]

I'm an experienced LR user who has been helping a friend install LR on her Mac, and have come across an issue I have never seen before. Her photos are on an external hard drive in a couple of folders (which show in Finder), but when we try to import them, no folders  show in"source" when I try to drilldown on the hard drive name in the import window (although all her photos are available).

"Include in subfolders" is on and "show folders in subfolders" is ticked on in the library. 

When I drilldown on her internal drive in Source, I do see the folders on that drive, but again there is no drill down available for the external hard drive and no folders show at all. 

[JohanElzenga]

Check in MacOS System Preferences that Lightroom has all the necessary permissions:

[GoldingD]

Is the MACOS Catalina or newer?

https://en.wikipedia.org/wiki/MacOS_version_history

If so, perhaps this is a security and privacy issue, see:

https://support.apple.com/en-gb/guide/mac-help/mchld5a35146/mac

and

https://nektony.com/duplicate-finder-free/folders-permission