I'm new to the community, but I noticed this too. First noticed when the I couldn't choose a Profile picture from my Drive Folder. Upon closer inspection, the File browser doesn't list anything from Drive. This is a huge setback since the seamless integration with Drive, Docs, Sheets and Slides was one of the primary benefits of Chrome OS and Chromium OS. I looked in the Dev community and there doesn't seem to be any mention of this bug anywhere. I am presently using Platform 5111.0.2013_12_13_1210 (Developer Build tonyd) which is a little out of date, but I had the same problem when I did the newest build from arnoldthebat about a week ago.