After seventy-five days you can place a service request with USCIS. Additionally, you can make an expedite request if it appears the EAD will not be adjudicated in time. On January 17, 2017, a new rule went into effect that grants an automatic extension of EAD work authorization for 180 days past the expiration of an expiring EAD when the EAD is based on a pending I-485, and the extension application was filed on or after January 17, 2017.
Are you sure about the extension application being filed on or after Jan 17 2017, please verify. It is my understanding that the fact sheet says something different.
"Employees with a timely filed EAD application that is still pending may qualify for the 180-day automatic extension, even if that application was filed prior to the effective date of this rule (Jan. 17, 2017). Eligibility for the automatic extension depends on these requirements:"