iMac thumbnails not showing for JPG and ARW images on drives

This was very helpful. Even after updating to the public 15.8.1, my thumbnails were still not showing up. I selected my pictures file, went to View as you suggested above. Then I selected "Show View Options", then I selected "Show item info" and "Show icon preview" and "Show preview column". That fixed ALL of the issues with the thumbnails. Now they are showing up again! Thanks for this as your suggestion was the only one that suggested going to the View option.

You'll probably have to do this with all of the folders on the external drives but try with the drive's top window itself and see if it will trickle down:

1 - wile in the Finder with an open external drive open select the View ➙ Show View Options menu option:

2 - in the View Options window click the checkbox Show Icon Preview at the bottom:

While there you can increase the font size and icon size.

Thank you Old Toad. Yes I gave that a try before asking for help on this forum. Unfortunately it did not help. I further searched this morning and did find a comment about a bug in Apple's release of macOS Sequoia 15.8:

Running macOS Sequoia 15.8 explains exactly why this is happening. You have run into a widespread known bug specific to the macOS 15.8 update.

This specific update introduced a regression that disrupts Apple's native RAW image handling. When Finder encounters a folder with camera RAW files (like .ARW, .CR2, .CR3, or .NEF), the background imaging service crashes. This crash instantly breaks thumbnail generation for all subsequent images in that session—which is why your PSDs and some of your JPGs are suddenly showing as blank or generic icons.

Give thia a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists.  Reboot normally and text again.

Note:  if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode.  This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.

Then try the Icon Preview method again.

E-P7 wrote:

Can someone please post the direct link for reporting to Apple as we photographers need our Macs!

For reporting macOS issues to Apple, use > Feedback - macOS - Apple

For other hardware and software products, use > Product Feedback - Apple

I just wanted to add that I too have the exact same problem in 15.8, RAW and Jpg.

Sequoia worked fine until I did the update.

Quicklook not working either.

I will be updating to MacOS 27 soon, but in the meantime I need to know that Capture One is okay.

M4 MacMini. 24gb RAM.

Can someone please post the direct link for reporting to Apple as we photographers need our Macs!

As far as I’ve always understood, Apple don’t monitor these forums as closely as they do messages sent to them directly. So it’s best if we all send direct messages to Apple to stand the best chance of Apple acting on them. This is a pretty serious matter so I’m sure a patch will come soon enough.

In case you have not done so yet, go through the process to upgrade to Sequoia 15.8.1. Apple spooled that out yesterday (9/28). The problem is solved. Thanks for everyone's participation in this issue.

Vuduvet wrote:

This was very helpful. Even after updating to the public 15.8.1, my thumbnails were still not showing up. I selected my pictures file, went to View as you suggested above. Then I selected "Show View Options", then I selected "Show item info" and "Show icon preview" and "Show preview column". That fixed ALL of the issues with the thumbnails. Now they are showing up again! Thanks for this as your suggestion was the only one that suggested going to the View option.

You're welcome. 👍

Vuduvet wrote:

This was very helpful. Even after updating to the public 15.8.1, my thumbnails were still not showing up. I selected my pictures file, went to View as you suggested above. Then I selected "Show View Options", then I selected "Show item info" and "Show icon preview" and "Show preview column". That fixed ALL of the issues with the thumbnails. Now they are showing up again! Thanks for this as your suggestion was the only one that suggested going to the View option.

You're welcome. 👍

Old Toad. Thanks (again) for your suggestion. However I think I am going to just wait for the patch I am assuming Apple will spool out eventually.

Thanks E-P7. This is a Community that accessed from the Apple site. Is it wrong to assume they already monitor it for problems that are pervasive? I do not do this much is why I am asking.

Thanks. Perfect!