I'm not seeing this behavior on my system, but then we use Windows, so this may be a Mac specific issue.
I am concerned about this statement: "I open the database with full access from a client machine on the local area network and make some additions to the database: (1) I add a new field to a table"
Adding a new field to your table while it is in use can be dangerous. FileMaker briefly locks tables and records when you make modification in Manage | Database and then click OK. If a user is running a script at that same exact moment, the "lock" can keep a step in the script from modifying data in a record as expected. And no error message is generated to tell you that this happened. You only discover this when the script does not produce the change expected or you audit your data and discover discrepancies...
For that reason, I recommend not defining fields on a "live" system. I wait until after hours to make this kind of change, or make changes to a new copy of the file and swap them--importing data as needed--after hours.
Thank you for your post.
I do not have access to a Mac OS X 10.6 Server at this time. I have tried this with FileMaker Server 11 on Windows 2003, Windows 2008, and Mac OS X 10.5 Server. Accessing the files as a guest from a Mac OS X 10.5.8, Mac OS X 10.6.5, and Windows XP SP3, I am able to add a field to a layout, and the change is immediately displayed on the other guest machines.
You mention "Typically, any changes that I make are instantly seen by everybody on the network." Assuming this worked previously, what changes have been made? Does this editing problem only occur with this particular file? Or, does it occur with all files on the Server? If you make changes from another client on the network, do the changes occur instantly?
I'm trying to narrow the focus a bit, so any testing or information you can provide may be helpful.