The I-485 is necessary anyway when an I-140 is filed.
Even though OP filed the I-485 NOT based on the I-140, they would still need one.
The I-485 has not being processed yet, so there should be a possibility of USCIS taking that form as part of the I-140 and not as an AOS from the O1.
Based on old threads I've read, it can delay the process as the applicant will need to go through some sort of rehab program for a year if I remember correctly.
This is one of many articles you will find when searching I-140 and I-485 concurrent filing:
https://www.greencardlawyers.com/greencards/adjustment/ConcurrentFiling.html
It has nothing to do with you; it is all about them and their circumstances.
They need to prove they have the financial means to travel to the US and stay for whatever amount of time and they need to demonstrate they have strong ties to their home country.
Where are they from?
Well, that is the risk I guess: if you attend the interview, the AOS process would be considered as abandoned and it depends on the consular officer if any visa the applicant has is canceled or not; so if the EB is not approved or it is delayed, you'd be unable to return to the US.
And not sure why the USCIS should recall the approved I-140. It is my understanding that processes can run concurrently.
The thing is that as a dual citizen, you can keep using the expired UK passport to prove citizenship - and in this case, avoid ETA- and the other unexpired passport to board the plane, train or ship.
It's from the Parliament's website, and refers to those who hold dual citizenship.
And on gov.uk it states that: you will not need an ETA if you have either a British or Irish passport (they don't specify if unexpired).
But just a few countries will need that by the end of this year. The US is not included, so far.
And even then, as per the Home Office: "Where the passenger claims to be British, but does not hold any evidence of British citizenship, the officer will conduct all relevant checks to satisfy themselves the passenger is British."
I think you can go to the interview. Not sure what exactly would prevent you from attending.
Whether AOS from O1 or EB2, the goal is the same: becoming an LPR. You'll get there quicker if approved in May at the embassy/ consulate.
It is very similar to what some applicants have been doing lately, filing an IR1 and K3 at the same time.
If your card is truly lost, you don't need to pay again.
You can file an e-request here:
https://egov.uscis.gov/e-request/displayNDCForm.do?sroPageType=ndc&entryPoint=init
And read the thread @Mike E shared. It details exactly how to make sure you get a replacement without paying the fee again.
Hopefully it ends up arriving to your home sometime soon. But insist with the postal service: your postman, your local post office and even the distribution center.
You're welcome mate.
And fear he should not, as e-gates can be used by citizens of the following countries: UK, European Economic Area, Australia, Canada, Japan, Singapore, South Korea, Switzerland and USA.
So it's just scan and go!
Some more information on the matter from the Home Office:
"When dual nationals who are eligible to use e-gates travel to the UK, they will enter via the e-gates without being examined by an immigration officer."
So @elmcitymaven, your ex can use the e-gates at Heathrow using the US passport. He's just visiting, right?
I fully understand your desperation.
Try going again tomorrow: you might encounter a more helpful employee.
At this point, even if you go full on Karen mode, it is worth.
You can contact the consulate to get some sort of letter to confirm the change.
And yes, you will need to pay the fees when your category becomes current, which will be around 2045. I guess the fees will be higher then.
Not that I'm stubborn or against mods decisions but in this case it is important to state that as per the HM passport office, british citizens that are dual nationals may choose to present a valid national passport in either of their nationalities at the UK border.
Honestly? None.
It is just for reference and to avoid being flooded by inquiries.
Things can happen way faster or way slower than what those processing times state.
I would use the I-130 form and the NVC case number - the IR1 visa one-.
BTW, for whatever issue at point of entry with CBP, there's something called "deferred inspection" where they fix mistakes made by other agents.
Every passport has a different number, and that's not what makes it valid or not; it is the hole that actually makes it invalid - that's why every country requires the old passport and returns it with some sort of damage-.
OP has the old non expired undamaged passport.