Unable to import into Photos from iPhone over USB? I've been trying to sync Photos from my iPhone 5S to my rMBP. I connect with an Apple-branded 3 foot Lightning cable, and I'm able to sync to iTunes with the cable, but Photos for whatever reason is not acknowledging that my iPhone is plugged in. 

Therefore, I don't get the additional Import button on the top of the Photos window. What steps can I take to resolve this problem? 

Note: rMBP running El Capitan beta build 15A278b and iPhone 5S running iOS 9.2.
One of the fixes in OS X 10.11.2 is:


  Fixes an issue that prevented importing photos from an iPhone to a Mac using a USB cable.


Source

Use the App Store’s Updates tab to install the update. 

Why are you still on an old beta build? It's not advisable to rely on a beta operating system; it’s in a state that Apple hasn’t yet deemed as being stable enough for daily use. Even if you don’t have any problems now, you may end up having some as apps and drivers get updated. You’re also missing out on the latest security fixes.