I am having this same issue, and it also occurs with the new Photos app. I use a Nikon D90 and D300s and Sony RX-100. I also use a Canon S90 but have not imported any photos from it since the 10.10.3 update. I have Aperture set as the app to import photos when a camera is connects. When I insert an SD card for the D90 or D300s, Aperture will launch but stay in the Image Browser. It no longer goes directly to the Import window as before. If I select Import I will get to the Import Window and see the memory card (as shown above). If I navigate the file structure and get to the folder on the SD card that contains the image files, then they will show up in the Import window and I can select all and import as before. A pain, but eventually I get them in through the normal import.
The RX-100 is a different story. The same behavior above occurs and the SD card shows up, but it does not allow me to navigate to the file structure (as described above). I have to go to the card through the finder to move the images into Aperture. If I select all RAW+JPEG pairs and "drag and drop" on Aperture it will tell me all files are imported, but it only imports the JPEGs. Then I have to go manually drag and drop all of the RAW files to them into Aperture. This is terrible!!! My dad is having this exact issue with his Leica D-Lux 5.
I am not really using the new Photos app yet but have some images in it. I have only tried importing from the RX-100 and it exhibits precisely the same behavior as Aperture. If I insert the SD card from the RX-100 it will show up in the Photos Side Bar, but I can not navigate the card and I can not get Photos to import any images from it.
So, the MacOS 10.10.3 update has hosed up the system-wide photo import function and it impacts both Aperture and Photos in what is precisely the same manner based on my experience. I have no experience with iPhoto. This is really terrible and extremely frustrating.
