Show referenced file in Finder is greyed out.
iPhoto will show any original file in the Finder, while Photos will only reveal referenced files. II meant you to try ""File > Reveal in Finder > Original file" on the original iPhoto Library you migrated to Photos to check, if the original iPhoto Library still contained the missing files, or if they already had been lost from your iPhoto Library.
Or did you not update iPhoto to version 9.6.1 so you can still use it?
If the originals cannot be accessed, the thumbnails are all you can get to show the photos, and then they will be pixelated.
Ctrl-click the Photos Library and select "Show Package Contents". In the window that opens, look for a folder "Masters". It should contain the full size original image files, in nested subfolder Year > Month > Day of import. Can you find the originals for your pixelated photos there? Are the photos in the full resolution?
Do the same for the original iPhoto library and inspect the Masters folder there. If your iPhoto version is older than iPhoto 9.3, the Masters folder will not be there, but a folder "Originals" instead.
I got a thumb drive and went into /Users/name/Pictures and dragged iPhotos Library onto the thumb drive. After it copied, I plugged it into my iMac and opened the iPhotos Library.
Is the file system on this thumbs drive MacOS Extended (Journaled)? If not the transfer might have caused the missing files. I'd repeat the transfer with a drive with a MacOS Extended file system and the
Ignore Ownership flag set,
See: https://support.apple.com/en-us/HT201517
- Select this drive in the Finder.
- Choose File > Get Info.
- In the Info window, find the Sharing & Permissions section. You may need to click the disclosure triangle to see the details for this section.
- Click the lock in the lower-right corner of the Info window. Enter an administrator name and password when prompted.
- Select the option to Ignore Permissions on this volume (usually selected by default).
- Copy your library to this drive.
