If you select multiple images in Aperture and then try to send them to Adobe Photoshop simultaneously using the Open With External Editor command, it's possible that only one image will open in Photoshop. This behavior depends on your color settings in Photoshop.
To see your Photoshop color settings, choose Color Settings from either the Photoshop or Edit menu (depending on your version). In the Color Settings dialog, if you have the "Ask When Opening" checkbox selected for both "Profile Mismatches" and "Missing Profiles," this is most likely what is causing the issue:
It's up to you to decide whether or not to have the Ask When Opening feature enabled based on your own technical needs and preferences. However, if you want to send multiple images from Aperture to Photoshop, you will need to deselect both checkboxes and then click OK.
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