Many employers have been reporting H-1B approvals with expired validity period, for example, the petition was approved on 02/17/2019 with an expiry date of 12/31/2018.
In these cases, the petitioners may file NUNC PRO TUNC request for extending the status. If the employee is working at the same location, you may have the LCA valid from the expiry date, you can use that LCA for filing extension from the expiry date (e.g. 01/01/2019 for the cases expired on 12/31/2018) explaining the reasons for the delay.
Nebraska Service Center is reasonable in considering NPT H-1B extension cases where the petitioner received approval notices after the expiry date.
If the work location has already changed and you do not have an LCA to cover the period immediately after the expiry date, it may adverse the NPT decision.
For successful NUNC PRO TUNC request, you must show that (1) the late filing is the result of extraordinary circumstances beyond the control of the applicant or petitioner and the delay is commensurate with the circumstances; (2) the foreign national has not otherwise violated her/his non-immigrant status; (3) the foreign national remains a bona fide non-immigrant; and (4) the foreign national is not subject to deportation or removal proceedings.
Our office has received many “Nunc Pro Tunc” extension approvals in such cases. You must consult with an experienced immigration attorney before filing an NPT request.