-- did your previous employer withdraw your I140?
No. they didnt, You have to make sure they dont do this, becuz it could trigger intend to deny.
--after you filed AC21, was the I140 approval sent to your new or previos employer?
It was sent to lawyer.
-- how soon did you file AC21 after leaving the previous employer?
Immediatly, with employmenet verification letter stating my job title, salary and responsibilities.
-- what's involved in filing AC21? Is it just a letter from your new employer stating your title, salary, responsibility, etc? Does the new company have to disclose any financial information
My lawyer sent letter to INS stating only thats my client is using AC21 and attached the letter employement verification letter. No new compnay didnt have to do anything.
1. Have your New employer filed AC21 before any I-140 RFE or as a response to RFE?
I am not sure about your question, but new employeer didnt do anything. They didnt have to.
2.Has your OLD employer ever had any history of denials/RFEs on 140s?
No. I was the first employee which they sponsored.
3.Can we file AC21 as a response to RFE about 'Ability to pay'?
Not sure about this. Need to ask lawyer.
To summrize this, I think you can change the job after 180 days of I140 and its better to inform ins about this. AC21 states about 180 days of pending I-485.
I would have gotten my I-485 approved also at the same time but becuz of doctor, which didnt specify about vaccination history, I got RFE.
Wish you all good luck.