Issue with photos

[one1]

I booted from external and wiped my internal HD on my iMac (late 2k9 3.06ghz, 8gb, 500gb). Setup El Capitan, fully updated. Everything works well, other than Photos. I have 6k photos in the cloud. Setup Photos and let it load everything, clicked download originals to my iMac. Closed it and reopened with Command-Option and rebuilt the database. It says in preferences that iCloud that the computer has backed up and is fully complete. After 2 attempts to rebuild the database My issue remains.

I can open any photo up to 3/4 of the way into my list of photos. The last 1/4 or so just throws the exclamation point error when expanding it from thumbnail, leaving my remaining 1500 or so photos inaccessible.

 

[one1]

I figured out the issue, but still no solution. After browsing the library contents I noticed the photos not showing (later photos in the library) were after my iPhone updated to ios11 and started using HEIF format. Apparently Photos cannot display this content (weirdly). So while I now know the cause, I still have no solution as these are iCloud synced photos so I cannot do anything about the library format. So, Apple caused the issue.....