Import from Olympus TG-4 in Sierra Not Working

I have an Olympus Tough (TG-4) camera which I shoot in RAW + JPEG mode. I've successfully linked the camera via USB, before, and imported to Apple Photos on OS X El Capitan. I recently upgraded to Sierra, and now am having problems.

Here's what happens:

I connect camera and go into Photos, and the import screen shows-up. There is an icon for each photo on the camera, but no preview of the actual photo -- just the grey, "generic" image icon. When I attempt the import, I get the "Unreadable files" screen, and all the photos on the camera are apparently unreadable. For the JPEG files, the message is "unable to get metadata." For the RAW (.ORF) files, the message is "couldn't be opened because there is no such file."

Very odd -- I had no issue prior to the Sierra upgrade.