Bookmark icons in Nautilus
Solution 1:
Seems that there is some trick around Nautilus, since I was able to reproduce the same behavior in Debian. But, just in case, try to re-set the icon for the Dropbox folder:
- Right click the directory/folder.
- Click Properties.
- Click the "Icon" besides the
Name:. - Look for the desired icon or hit Revert.
The changes should be immediate, but in your case a log-in/off might be necessary to verify that everything is in order.