Yes, failing to disclose or disclosing an inaccurate file number (File#) in the closing information section on page 1 of the closing disclosure violates section 1026.38(a)(3)(v), part of the TRID rules in Regulation Z. If this is a recurring error in your mortgage loan files, the bank could be cited by examiners. Otherwise, I consider it a minor technical violation.
Your best reaction to discovering such an error in a review or audit would be to determine whether there is a pattern of such errors that points to an individual, or, in this case, a particular settlement agent, and then to work with that individual or settlement agent to correct procedures or controls to mitigate the risk of such errors in the future.
Of course, if the bank does not use a settlement agent for a loan, there should be no entry in the File# field. And if the bank's settlement agent does not use file numbers, leaving the field blank will be correct.