US Immigration from Pakistan

I just received this update on my husband's status:

On July 8, 2021, we cancelled your interview for your Form I-751, Petition to Remove Conditions on Residence, Receipt Number XXXXXXXXXXXXXXXX, and mailed you a cancellation notice. We will notify you by mail if the appointment is rescheduled, a decision is made, or if we need something from you. Please follow any instructions in the notice. If you do not receive your notice by August 7, 2021, please go to www.uscis.gov/e-request to request a copy of the notice. If you move, go to www.uscis.gov/addresschange to give us your new mailing address.

They originally scheduled it for August 11. I've read somewhere it could be a glitch? Is that possible? I'm confused. Would it take another few months just to reschedule? I hope not. We have been waiting for 2 years.....

Hopefully to receive the NOA2 within the next 30 days but due to the work overload (the 6 working days a week) we wanna get ready all the related documents from now so to avoid the odds. kindly share your experience regarding the responsibilities of the petitioner just before or after the NOA2 . Like what type of document should I prepare and what to be done with those documents? Thank you in Advance.

Few year back my US Visa application was revoked, Now i'm filling for new Visa application, However i'm confused with the question in DS-260,

have you ever been refused a u.s. visa, been refused admission to the united states, or withdrawn your application for admission at the port of entry?

Should i answer it "Yes" or "No" because my visa was not refused but revoked ?

My sister is sponsored by my mother in 2006 as unmarried daughter of Permanent resident (at the time of filing my mother was a permanent resident) now she is a citizen. My sister aged out while we all got to the US.

My sister got married in 2008 and then had a daughter as well, both her husband and her daughter were added to the petition.

My mother became a citizen in 2011 and informed the USCIS about her status change as well.

I have three questions and if someone can help me I will sincerely appreciate.

1) the Application on CEAC shows At NVC, what does that mean?

2) unfortunately my sister is now going through a divorce, would that negatively impact her application? Will her husband (separated at the moment and soon to be divorced) will he be able to get the immigration visa as well? Considering they have a child together? Or any other thing that can or will happen to the petition?

3) what dates are currently being reviewed based on that initially it was a permanent resident applying for unmarried daughter and then it was married with kids and the status of PR changed to USC?

Really thankful in advance for any and all insights.

Beneficiary is in Pakistan and a Pakistani citizen.

Thanks

Hye guyz !! I am From Pakistan and living in Pakistan my wife is American my interview is coming after some days everything is going smooth in our case but for interview day i have a question we have a age gap relationship my wife is older than me . We have screenshots of our daily conversation we have alot of evidence but i am lil bit scared about age gap so what is the best answer to satisfied the consular... Any good advice please i will be very grateful. Thank you