Answer
From the Setup History Log window, right-click on the navigator tree and enable 'Show Foundation 1 Component' — this reveals an additional 'IFS Base Functionality' node in the tree that isn't visible by default, containing framework-level LUs (including ones like FND_CLIENT_LOGON_TAB) not shown in the normal view. Open that node and select the specific table's LU from there to access its History Log entries.