Finder does not consistently show JPEG thumbnails

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

IMPORTANT:

Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:

Also click and read the About info to further permit full disk access.

Then we can examine the report and see if we can determine what might be causing the problem.

Are all of the problem files from the same source or camera? If edited make sure the editing app attached a preview icon to the edited file. Some apps have the option to not include an preview image.

Hi narya638,

Welcome to Apple Support Communities! We understand that your Finder only shows thumbnails for some of your photos and you would like to correct this. Those are great steps you've taken so far.

Next, we recommend going through the steps in Get help with the Photos app on your Mac.

Repairing the Photos library might help as well. You'll find those steps in How to use the Photos library repair tool.

Best Regards!

narya638,

Thanks for giving those steps a try. Since this issue is still occurring, lets have you reach out to Apple Support directly from the link below:

Get Support

Cheers!

I have the same issue ever since upgrading my iMac to OSX 10.15.7 I have verified that show icon view is ticked for the folder I can view the images in Preview. Inspector shows a blank grey though. I rebooted. I do not use Photos at all rather just have these jpeg images in various folders. The psd files in the same folder are all showing their icons just not the jpegs. Any ideas of how to fix this??

also TIF image previews are showing. So it appears to be a jpg issue only. this is true for full sized jpg files as well as web sized ones

sorry, Inspect does show data for some of the tabs.

bestsides wrote:

Thanks I will give that a try. In briefly checking a few image folders it appears that the issue is isolated to those on my EHD. I

How is that EHD formatted?

You might try creating this automator workflow/app and try it on a couple of test problem images to see if it will generate the preview ion:

Just save it as an app and drag and drop the image files onto it. Be sure to test first with copies.

Thanks I will give that a try. In briefly checking a few image folders it appears that the issue is isolated to those on my EHD. I tried deleting the com.apple.plist (instruction/suggestion found on web search) but that didn't fix the files either. I was wrong, in my above statement that it only affected jpg/jpeg files - a handful of psd and tif format extensions are not displaying their icons either but rather defaulting to the generic. This is despite everything looking fine in Preview and in the Get Info Preview ...it just won't display them. I'll look at trying to fix a few view Automator as you suggest and then reboot to see if these fixes "set". I did open a psd, resave it, as well as re-export a web sized jpg and those previews then showed. Unfortunetly it would be a big time suck to do this (even with batch programming/scripts). I wonder if this is related to the other issue of not being able to drag images from an EHD to Messages. With Catalina we now have to drag (copy) the web-sized or jpeg images to the desktop (internal drive) first then do a subsequent drag of the image to the Message window. Such a PITA. I have found other frustrated Apple customers complaining about this. It has been suggested it is a side effect of new security "features". I wish Apple would alert customers to changes of this type in their summaries of the new updates. They give us the positives but let us figure out the bugs and undesirable changes for ourselves. I never would have upgraded from Mojave if I knew just how much work Catalina was going to introduce.