EAD (WorkPermit)

I have learned a lot from other posts, so I would like to share my experience here. Hopefully it will be helpful to whoever is dealing with similar issue.
Sep 27, 2017 - Mailed my OPT-based I-765 application to the Lockbox
Oct 2, 2017 - Case was received
Dec 19, 2017 - Service request asking for a status update
Dec 23, 2017 - Response to my request: case is under review, should receive a decision within 30 days
Jan 9, 2018 - Case approved after 100 days
Jan 11, 2018 - Card is produced
Jan 12, 2018 - Card is mailed to me
I called USCIS right away and a Level II officer provided me the tracking number
Jan 15, 2018 - Approval notice received in mail (NOT the actual card)
Jan 17 – Jan 31 - Card lost in transit (There was no updates for this piece of mail. I called USCIS customer service and was told that I basically had two options: file a EAD replacement or wait for the card to be returned. Once I file a replacement, the original EAD card would be invalid, so I decided to wait a little longer)
Feb 1, 2018 - Card returned to USCIS as undeliverable
I called USCIS and request to resend my card
Feb 9, 2018 - Response to request: the card will be redelivered. Contact USCIS again if not receive in 30 days. I thought my card would be here any minute.
Mar 1, 2018 - Another request to USCIS for status update and expediating my case
Mar 6, 2018 - Response to last request: card will be resent. Contact USCIS again if not receive in 30 to 60 days.
Mar 6, 2018 - Mailed casework form and all supporting documents to State Senator Office
Mar 15, 2018 - An attorney from Senator’s Office got in touch with USCIS officer, and the response indicated my card will be delivered within 20 days.
Mar 16, 2018 - EAD card remailed to me
Mar 19, 2018 - Card delivered in my mailbox

Some tips:
- Download and signup USPS informed delivery. It helps to track all the incoming mails. Always ask for a tracking number after the card is mailed out.
- If unfortunately your card got returned to USCIS as undeliverable, do not expect it to be resent soon. It could take USCIS up to 90 days to remail a card. Based on my experience and correspondence with USCIS, it would take approximately two months to process this request.
- In the case that a card gets lost in transit or returned, I suggest to file a EAD replacement because the replacement receipt notice can be used as a work authorization and give you 90 days to work without the physical card. However, some companies may not accept this, although it’s legit. So consult with your employers before make any moves.
- My card was returned to an office in Missouri, but I couldn’t get in touch with any internal personnel who actually works there. Due to an increasing number of undelivered cards, from what I heard, the approval notice plus the response from USCIS indicating the card will be remailed can get you started on the job. But again, some employers do not accept them as valid documents. It is totally a discernment of your employer.
- The entire process took about six months, and it was very stressful, especially given the 90-day unemployment period for F1 visa holders. Starting March, I felt that my clock ticking and panicked. I basically contacted and tried to get help from anyone I could think of: school OIS, my employer, State Senator and USCIS customer service. In my case, the attorney from Senator’s office was a huge help!
I wish no one has to go through this process. Good luck to you all~