Back story: I have iCloud Photos turned on.
I changed my photos settings from the “optimize storage” setting, to the “keep original copies on this computer” setting.
This change initiated a download from iCloud of all my photos to my hard drive. After 3 days the photos app paused the download—due to not enough system storage.
I closed photos. Went to my photos library and copied it to an external hard drive.
Once the copy was complete. I double clicked the new photos library to open the photos app and set this as the new photos library.
When photos opened I chose “use as system photo library” then the pinwheel came up and has been spinning for a few hours now!!
Should I wait and let it keep working? If so, how long?