Please see this thread:
And to be clear: it's not that .r3d files are not supported in After Effects 13.7.1 on Mac OS, it's that there is a bug. We're working on a fix for this, the workaround in the meantime is to copy the files as described in that thread. Our apologies about the bug.
(ingstar, I believe I already replied to your request to send the files. Let me know if you have any issues with them.)
This is really killing us. We're in "crunch time" and have a team of people trying to work the weekend to hit a deadline. Our systems seem to have auto-updated and so now we can't connect to our red files.
Can you send me the files I need ASAP?
Also, how do we keep apps from auto-updating?
You don't need the files from anybody else. A user in that thread (that Tim mentions in his "correct" post in that thread) tells you how to grab those files from your Premiere install to fix it.
Well, as it turns out, I grabbed the files from another system which had not auto updated (so it was running AE 2015 version 13.5, but it did not work).
Try grabbing from the updated Premiere files.
And then restart your computer.
This bug is fixed in the After Effects CC 2015 (13.7.2) update: http://adobe.ly/1WaV0pP
This bug-fix update fixes only one bug that occurred in After Effects CC 2015 (13.7.1) on Mac OS X: RED (.r3d) files can again be imported, and are not reported as missing in existing projects.
This update is for Mac OS X only and is not available for Windows, because the bug with RED files did not occur on Windows. The most recent update for After Effects on Windows is After Effects CC 2015 (13.7.1).