Hi Stephen,
I’m still running High Sierra on my Macs with no intention of upgrading.
To give a suggestion to the problem you are experiencing, have a read at this 
link.

https://www.apowersoft.com/transfer-iphone-photos-macos-catalina.html
Best Ways to Transfer Photos from iPhone to MacOS Catalina

“Image Capture is a built-in tool made to import photos from iPhone to macOS 
Catalina. Most of the Mac users are not aware about this tool. It allows you to 
easily transfer photos from iPhone to Mac. Just search it thru the search tool 
or you can find it in the “Other” folder in the Launchpad or in the 
Applications folder.”

Kind Regards,
Ronni

 Ronni Brown’s iPad Pro 12.9-inch 256GB 


> On 23 Oct 2019, at 10:48 am, Stephen Chape <[email protected]> wrote:
> 
> Hi folks.
> 
> Another Catalina conundrum ?
> 
> I open Photos on my iMac and then plug my iPhone into my iMac.
> 
> When I then click on “iPhone" in the sidebar, the photos on my iPhone are 
> shown as greyed out squares.
> This means that I am unable to see which photos I would like to download 
> (because there is no thumbnail).
> 
> This was not the case before Catalina.
> Any ideas please ?
> 
> Regards,
> Stephen Chape
> 
> 
> 
> 
> 
> 
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