Adjustment of Status - I-485

Hi all. I met my USC hubby in 2013, after I had moved here on F-1 in 2011. We married in oct 2015 and applied for AOS Oct 2016. We had our interview on Sept 2017. It went well except we couldn't exactly remember the exact date we moved in together and also mentioned we live together 50% of the time as he travels for 2 weeks for work every month. My husband mixed up my place of birth and where I grew up. Anyway, the interview was 45min and pleasant. When we were done, the IO told us everything looked good and he couldn't approve us on the spot because he was new and his supervisor needed to review the file to make sure he got everything that was needed but he would recommend us and assured us to look out for a decision in 30 days. So 4 inquires and USCIS ombudsman help and 1.7 year's after our interview, we were informed that our file was placed in records center( which is where they store files that are completed and a decision has already been made) they asked to give them 30 days to request it and to review and will give us a decision in 30-60days. 2weeks later, I receive an interview letter. It states we are going to be there for 3hrs and should bring our tax records, employment letters, new medical records, weddings photos, lease agreement, insurance,deeds,bank statements and anything that might show our marriage is bonafide.
I'm guessing this is a stocks interview. My question is, why would they think my case was done and then decide to interview again? I think the IO that interviewed us is no longer there.
Has anyone ever gone through this? Any advice is welcome and yes we will be getting a lawyer so we're better prepared. I feel like last time, we didn't take all needed documents. I forgot to give them sponsors t
Any insight is helpful.