I have my iPhone setup to open Photos app when I connect my iPhone to my Macbook Pro. I also have Dropbox automatically importing my photos when connected too.
Dropbox has no problems importing my photos, but Photos does. I can see my iPhone connected, but I can't see any photos on my iPhone as you can see from this image: (The name "Hold Me, Touch Me" is a reference to movie "The Producers" with Zero Mostel.). As you can see, the name of my iPhone shows up, but not the 168 pictures on the phone.
I suspect there is some [i]security setting[/i] where I have to tell Photos it has permission to read my iPhone, but I can't seem to find it.