A few of our customers running OS X 10.10 have had an issue with files not showing up in finder. This is especially obvious if they're using Dropbox.
Dropbox usefully adds a green tick for files and folders that have synced.
"That's weird... the file you've just uploaded isn't in my dropbox yet but all my files and folders are ticked green"
The problem is that Dropbox has done it's job and the files and folders are in sync it's just that Finder isn't showing you your files. We can tell that because if you click on the Dropbox icon in the menu bar and select one of the recently updated files it will refresh your finder window and show you all the updated files...
Why is this happening?
Well... We're not sure! We've told Apple about it and so have a bunch of other people but Yosemite's been ding this since the beginning. It's to do with the 'cloudd' process that's running and in particular one of the files that it accesses. Basically it's corrupting one of the files it needs and that makes Finder hang (not refresh itself).
DISCLAIMER: Please make sure you have a backup before you do anything in Terminal - We will not be held responsible for anything that goes wrong (but we'll help you sort it out if it does).
There is a way of resolving this (please note the disclaimer above!)
Type this into Terminal:
rm ~/Library/Caches/CloudKit/CloudKitMetadata*;killall cloudd
That should resolve the issue.
You may need to do it again in the future, so just bookmark this page! If Apple release an update we'll update this page to reflect that.