Resolution:
This problem occurs when you do not explicitly apply changes before saving. If after making your changes to the Constant Field on the File Record you move the focus to another File Record, you will receive a dialog box warning you about data loss, this dialog box will also give you the option to apply the changes. If you select the apply changes button, save the project and close Designer, when you reopen the same project using Designer you will find that your changes have not been saved.

This problem can occur when making changes to any File Adapter value, until this problem is fixed the solution is to select the ‘Apply’ button on the form before saving the changes; this will ensure that all changes are written to the repository.

Changes to the Constant field in the File Adapter positional file record configuration sometimes disappear after reopening the TIBCO Designer.