Faux unreadable format errors when importing into Photos or Image Capture
Helping a semi-pro photographer. She's got a 2019 iMac with only a 256GB hard drive, so has needed to resort to an external SSD for most of her storage. She uses Lightroom & Adobe Cloud for her final edits and organization, but likes to go through a culling process beforehand, and prefers Apple Photos for this. Also, she typically plugs the SD Card from her camera in to the slot in the back of the iMac.
Last year, out of the blue, Photos started erroring out when importing photos from one of these cards. Basically it would go through the import process of for a few minutes, successfully bring ing in say 3000 images, but then gives a list of 200 or so, that were in an "unreadable format" (although same format as all the others.) Tried to make some rhyme or reason at the time, but what worked with first importing with Image Capture to a folder, then importing into Photos. Perhaps that says something about the SD card or card slot interface -- she's using high speed, name brand SD cards, and all of them exhibit the same behavior, once this problem arose.
Fast forward a year. Workflow has been working great ever since....until last week. Now the same problem is happening when using Image Capture -- it reports a few hundred out of a a few thousand are in an unreadable format. We try importing in smaller batches, and sometimes it helps and sometimes it doesn't. If we get a file the first is "unreadable" but later is readable, it opens fine in Preview and imports fine into Lightroom -- so I don't think the unreadable assessment is true.
She reformats her SD cards after she processes them to the point they have uploaded to Adobe's Cloud, so she' been through many cycles of reformatting where it has worked just fine. But perhaps it's something in the card the camera is reformatting? Or perhaps she's buying larger SD cards these days, and the camera is not quite handling them correctly? (just a theory).
I'm not a photographer, so am not familiar with the subtleties of camera cards and how to best format them.
Anybody recognize this problem? Or have a solution?