Adobe Community Professional, Apr 08, 2021Apr 08, 2021
Trevor.Dennis • Adobe Community Professional, Apr 08, 2021Apr 08, 2021
Just to be sure. Is the layer you have selected turned on?
I can't think of any other gotchas that would stop Merge Visible from working, unless the shortcut has been stolen. That can be within Photoshop, but also from another app like a screen capture app.
I use Windows and I'm not up with the OSX issues with Photoshop, but I do know they are legion. What version of OSX are you using?