Just sharing my experience here. My I-751 was pending when they scheduled my interview. The first thing I mentioned to the IO when I walked into the room was that my spouse is with me waiting in the car outside if you want to interview him. IO said they don't have my I-751 and decided to do a combo interview anyways. Bring updated bonafide marriage evidence with you. I kept my I-751 slim. Maximum of 7 pages mortgage, deed, airplane tickets, car insurance and photos. I-751 and N400 was approved on the spot.
Couple weeks after interview the I-751 got knocked lose and status changed "transferred to new office". Couple days after that I get a call from an officer saying congratulations my oath ceremony is now scheduled.
Stay hopeful and your time will come.