Externally edited images do not automatically appear in Photos (Mac)
According to this Apple webpage (Edit with third-party apps and extensions in Photos - Apple Support), externally edited Photos do NOT automatically appear in Mac Photos.
Key text from that web page:
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Edit photos within third-party apps on your Mac
With Photos for macOS High Sierra and later, you can send a photo to most third-party photo apps for editing, then save the changes right back into your library.
- Control-click a photo and choose Edit With from the contextual menu. Then choose from the list of third-party editing apps on your Mac. You can also click a photo and then choose Image > Edit With in the menu bar.
- The photo opens in the third-party app that you chose. Make your edits, and then save.
If the app saves photos in a non-standard format, look for an option to save as JPEG or another format that Photos supports.
Your edited photo appears automatically in Photos.
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I am testing Apple Photos to see if I can use it for image organization and management while using an external image editor.
I will guess that I am suffering from "pilot error" but I don't know where to start troubleshooting this.
My external editor is producing a JPEG, so I am at least avoiding that snag.
Mac Photos 10.0 (721.0.150) running on Sequoia 15.2
iMac 27″, macOS 15.2