I have been just putting up with this issue for several months. Some of the thumbnails of my images in the Photos app have disappeared. I have no idea what causes this phenomena, but it is a real pain to have to fix it. If you are having this issue, do not lose heart. There is a fix.
Photos Thumbnail Fix
Here is what we are looking at. When I opened the Photos app I noticed some (not all) of the photo thumbnails are missing:
I tried doing a “Repair” to the Photos library by holding down the Command ⌘ and Option ⌥ Keys while starting up Photos. The app asks if you wish to “Repair.” Tell it to go and it takes about 5 minutes, depending on how many photos you have. However, I did this twice and it did not fix this issue. I did some research online and discovered this page on the Apple Support site describing a fix for this problem. Here is the deal, if Apple has a support page for this problem, it is pretty much a common, known issue. Here is how to fix this. It is cumbersome and time consuming, but it pretty much works every time. FYI here, I would try the library “Repair” at least once. Apple says it is supposed to work. Perhaps it would fix your thumbnail issue, you never know.
In the Photos app select a bunch of photos with no thumbnails. If you only have a few here and there you can Command-Click select them individually. However, in my case, I had bunches of them so I just did Shift-Click at the beginning and end of several photos to get several at a time. Don’t worry about selecting photos with thumbnails, they can just go along for the ride.
Once you have a section of photos selected go up to the “Image” menu and select “Rotate Counterclockwise:”
This will rotate the selected photos to the left. Most of the thumbnails will appear using this procedure. When you are finished with that, then just choose “Rotate Clockwise” from the “Image” menu and rotate them back:
Your photos thumbnails should be showing. I have a very important caveat here!! If you are rotating lots of photos at a time or if you are rotating several RAW image photos which happen to be quite large you have to wait for the rotation to finish each time. When you rotate the photos, the thumbnails will appear fairly quickly. However, the actual photos are not finished rotating. If you look in the upper left corner of the Photos app menubar you will see this count down timer:
That little wheel is showing the progress of rotating the actual photos. If they are in the RAW format, this can take a bit of time. You should not move on to rotate the next batch of photos until this progress timer is finished.
By the way, I said this works most of the time. I do have a few photos where this did not fix the issue. Apple says to take the photo into the “Editing” mode and flip it or do some small thing to change it. Then supposedly, it will show. Also, even though the thumbnails are not showing, the photo is still there. You can export it to the Desktop and open it with another app.
This is such a hassle folks! Many of my photos are not showing the thumbnails so I am in the process of combing through my library get them all to display properly. As far as I am concerned, this is a real problem with the Photos app. Maybe it is just not designed to handle large amounts of photos, I just don’t know. Hopefully, Apple will fix this in future OS updates and/or Photos app updates. If you know what causes this please leave a comment. I would like to know. Also, if you know an easier fix, comment back to the blog so others can see it.