Photos won't allow me to edit.

You don't say what macOS your are using. And your you using iCloud to sync your devices? Do you have "Optimize Storage" checked in Photos>Preferences>iCloud?

Are you keeping your Photos Library on an external drive? To get full functionality (and to avoid damaging the Photos Library) an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted.

The error message is showing "cannot load edits". There could be several reasons for this problem, in addition to the file system format of the drive with your library, already mentioned by Richard.

• Do you have plenty of free storage on your Mac? A lack of storage could prevent Photos from loading the edited version.
• Or the edited version may not be compatible with the current version of Photos you are using. In that case it will help to revert the image to the original before you try to add new adjustments.
• If your photos library is syncing with icloud Photos, check for a problem with your internet connection. Third party security software could be interfering with the access to Apple's cloud servers.