Ho Ho Ho...
I answered my own question. In case anyone has the same issue:
This is found on page 19 of the ESS tech brief found at:
Manage the Field Structure of the New Table
When you first add a table from an ODBC-based data source to your schema,
FileMaker Pro creates a shadow table in the local file. The shadow table contains
field definitions for all of the fields in the remote SQL table. It is not possible to
change the definitions of these fields. It is possible to delete fields from the shadow
table. This has no effect on the SQL database itself. It only affects the fields that
are fetched and displayed in FileMaker Pro. Deleting from the shadow table any
fields you are not interested in is an effective way to limit the amount of data you
need to fetch from the SQL source.
If you need to restore deleted shadow fields, or
otherwise re-synchronize the structure of the shadow table in FileMaker Pro with the
structure of the SQL table on the server, press the Sync button near the top of this
Hope this helps.