Previews are still being created for edited photos.

The photos are 264 of about 2000 - 3000 that I took with my Canon camera in RAW format (Canon CRAW2) while on vacation in Yellowstone and Grand Teton National Parks. While I have not checked every one of the 264, I have checked some and they can be opened in Preview without issue. I initially imported them to an external hard drive on my Mac (LaCie) knowing that I would not have space for them all on my Mac and would only be able to import and share a few via Photos. I used an SDHC card reader transfer all 2000-3000 photos to the LaCie. I then viewed the phots via tge previews that Finder had no trouble creating. I have over 300 GB of disk capacity remaining on my Mac hard drive, and over 700 GB available on my 1 TB iCloud Drive plan. 264 previews should not be takibg up that much space. An average CRAW2 file is 23 MB, so 264 of them = 6 GB. There is plenty of capacity. There are no videos in the selected batch of photos. I have imported CRAW2 files directly from my Canon camera and directly from a SDHC card reader to Photos many times before without issue. All 264 photos appear in Photos on my Mac with thumbnails and when clicked on appear fine in Photos on my Mac. The problem occurs when I try to edit the photos - edits do not stick, or the photo shows as unedited in the thumbnail after editing (and if the aspect ratio was changed in the edit, the aspect ratio is all messed up in the thumbnail), but when you click on the thumbnail the edits suddenly appear when the photo is viewed large. This is happening with every one of the 264 photos that I imported. After waiting all night and with no progress in the generation of previews, I finally quit that process and exited photos. There is not an issue with the photo files or with capacity. There is now a problem with Photos and iCloud Photo Library and iCloud Photo Library that was not present before my vacation, and the only thing that has happened since then has been the latest Mac OS X El Capitan update and iOS updates, all of which were implemented on my iOS devices while on vacation, and on my Mac as soon as I returned before the 264 photos were transferred from the LaCie hard drive to Photos on my Mac. And none if the photos are showing up in All Photos, Photos, or Favorites on my iOS devices, although they do appear there on my Mac. Other photos that I took with my iPhone5 and iPad Air 2 on the same vacation appear fine on all three devices. It seems Photos, iCloud Photo Library and iCloud Photo Library can no longer properly process RAW files.

Sorry for the typos above. I used my iPad Air 2 to type it, and for some reason the touch on the iPad Air 2 keyboard combined with spelling checker frequently creates typos. The sentence that starts with "I then viewed" should read "I then viewed the photos via the previews that Finder had no trouble creating". Also, I did import the photos in small batches initially. I first selected the 264 images that I wanted to import to Photos on my Mac by viewing all 2000-3000 via Finder on my LaCie external hard drive. I dragged the selected 264 photos onto my desktop, placed them in folders in groups of 10 to 30 approximately, and then dragged the images in each individual folder into Photos one at a time. Previews for each batch appeared fine in Last Import In Photos. I selected the photos immediately after import and added them to a new separate album for each batch that had the same name as the folder that I dragged them from on my desktop. The photos appear in the albums on my Mac, but on my iPad Air 2 and iPhone 5, the new albums appear without any images in them. Photos on these devices state that there are no photos in the albums, which there clearly are. So Photos on my Mac appeared to import the photos just fine, but they cannot be edited (or they can but the edits are all messed up), and iCloud Photo Library and iCloud Photo Sharing will not share them with my iOS devices.

Upon further inspection, when I opened up Photos on my iPhone5 this morning, there were multitudes of photos that I had taken last Tuesday while on vacation with my iPad Air 2 and iPhone 5 that had no thumbnails showing in Photos on my iPhone 5 now four days later. So it was apparently those thumbnails that iCloud was trying to generate previews for when it hung, although those thumbnails were showing there previously at least on my iPad Air 2 and on my Mac. So Photos or iCloud Photo Library or iCloud Photo Sharing is definitely messing things up between my three devices. The problem seems to be in those applications and services. The only way that I could get the thumbnails to appear on my iPhone 5 was to scroll through every photo in my library on that device, which, after waiting forever, changed the blank thumbnails with a cloud to a photo thumbnail. In some cases scrolling did not make the thumbnails appear. I had to select the blank thumbnail, select edit, wait forever for the photo to download from iCloud and then the thumbnail appeared. Here are two of ten screensavers from my iPhone 5 iCloud Photo Library that I just took during this process. Note that in the second image it clearly shows that this is a photo that was taken on Tuesday (it is now Saturday) with either my iPhone 5 or my iPad Air 2. I could not upload photos from my Canon camera to iCloud while on vacation. So whatever messed up my iCloud Photo Library happened as a result of Apple Photos on my iPhone 5 or iPad Air 2, or Apple iCloud Photo Sharing services, not because of the Canon CRAW2 photos that I uploaded last night. As we are speaking, the thumbnails for the Canon CRAW2 files that I uploaded are ever so slowly beginning to appear on my iPhone 5 (6 out of 264 have taken over an hour to appear).

No Repair Library required for mine. I suspect that my problem was something different, but also sort of similar. Right before my vacation I accidentally dropped my iPhone 5 from my pants pocket in the toilet without realizing it, where it apparently floated until the morning when it was found. I took it to a local Apple Retail Store, but alas after 24 hours in a toilet no resuscitation was possible, and Apple gave me a replacement iPhone 5 (gave used euphemistically here, since my Apple Care Plan had long finished, and I had to pay for the replacement phone). I did so because we were leaving on a 2 1/2 week photo safari and vacation the next day to National Parks, and I wanted to be able to take some photos on the trip and be able to post them immediately to various social media. I use a Canon DSLR for my high resolution photos. Great resolution but no ability to upload photos immediately to iCloud, or get the photos into my iCloud Photo Library from my Canon camera without a Mac in between. And no Mac on vacation. To make a long story short, at the Apple Retail Store, iCloud TOOK FOREVER to restore my account. I literally sat there for three hours and all it did was get my iCloud settings restored and not my data. I believe that what you said about it just taking a long time to sync is correct. I think 2 1/2 weeks later, it still was catching up on syncing, no doubt because we had been traveling in locations with poor-to-no Wi-Fi signal. I also discovered over the weekend that when I finally connected my iPhone 5 and my iPad Air 2 to my Mac to see if physical syncing would help the problem, both iOS Devices wanted me to verify that my Mac was okay to be "trusted". Very weird. Both of the devices had been synced with my Mac right before my vacation. After saying "yes", magically syncs happened, iCloud Photo Library finished restoring in a relative blink, bizarre photo editing issues mentioned above stopped, and all now appears to be fine. Cannot explain the weird things that happened, other than, if you have a large iCloud Photo Library (mine has 20,000+ photos), just hope and pray that you do not have to replace one of your synced devices. Especially when an iOS and Mac update comes out while you are unable to access your computer. The good news is all is well now. So in the end, it finally just did work.