I played a bunch in the last couple days, unlocked lots o cheevos. I decided to go get the Trevor cheevo and it wouldn't pop for me. No matter what I tried or how I did it it wouldn't unlock. I checked the internet for answers and didn't find anyone that had this issue. I figured i'll quit the game from the home screen, turn off the one and try again. When I went back in and loaded my save it dropped HOURS of my gameplay! SPOILERS ahead I guess but it started me back where Cap and Thing were looking for the whatever ship before he gets his head stuck in the sand on the island. I had played through defeating Magneto and having him fall through the Fantastic 4 lab window! I was trying the Trevor cheevo just before talking to Fury on the carrier. Plus I had done some free play and grabbed a lot of gold bricks from the city and went back and free-played level 1 to completion and now it's all gone... :( I saved and continued at every terminal, saved and quit back to the city, I was always saving on top of all the supposed "auto" saves. Needless to say I'm nun too happy about it, no sir.
On the plus side, if there is one, I went back to the hover carrier and got the Trevor cheevo, weeeeee.... :P