If a computer has just had the agent installed and is still initializing, some of its files are available to Find Files, but its full file inventory is not available until initialization is complete.
To determine whether a computer is still initializing, go to the Computers page and search for the computer.
Similarly, if an agent is re-synchronizing with the server, changes in its file information are not complete until the synchronization is complete. You can view synchronization progress on the Computer Details page or, you can add the Synchronization column to the table on the Computers page.