Which exact camera? Which version of Camera Raw? What network drive? Does it work from a local drive? You need to provide much more info.
Cameras are Canon 60D (multiple camera shoot, same problem with all camera footage)
Camera Raw 9.1.1, After Effects CC 2015.0.1 (188.8.131.52) and After Effects CC 2014 (unsure of exact version number as I already updated to see if the issue was fixed)
The network drive can be any drive mounted from either my main file server or another computer on the network. I do have everything set to AFP because of a number of permissions issues that were happening with SMB, and all computers involved are running OSX 10.10.4. Everything works fine from a local drive, and as I mentioned if I choose the containing folder instead of a specific .cr2 file it will start importing them without an error. Also, importing any other type of file from a network drive works fine, including the .JPG versions of the .cr2 files in the same folders.
I can even use the Adobe DNG Converter to change the .cr2 to .dng files and then successfully import the .dng sequence off a network drive. And I can use Photoshop CC 2015.0.1 (20150722.r.168 x64) to open the .cr2 files off the network, using the same version of Camera Raw.
One final note - I have Thinkbox's Deadline software installed, and was successfully able to import a local .cr2 sequence into After Effects, set up a comp, and send a render to Deadline for a network render job. Meaning that other computers could access and open my local .cr2s for use in a render using the aerender application, but no computer is able to use regular After Effects to import a network .cr2 file.
On the similar forum thread I found from several months ago, that user eventually found with Adobe Support that his problem seemed to be down to a new issue with OSX 10.10, and an Adobe staff member said he was able to see the problem too:
Paul, thanks for following up.
I tested importing camera raw file types from a network drive and replicated the problem. It only happens on Mac OS X 10.10; on Mac OS X 10.8 and 10.9 I do not get this problem with After Effects. Also, it doesn't occur with some of the DNG files I tested, though it does with others. I'll file a bug.
We will need to investigate further as to what changed in Mac OS X 10.10, but thanks for providing the details.
After seeing that, I also filed a bug report early last week in case it added any relevant information.
I can also confirm that this issue remains in OS X 10.10.5 released yesterday, and from an Adobe Tech Support person on the phone that this is definitely still a bug registered on their system as being worked on.