I’ve also had this issue. My armor resets like everyone explains and my campaign won’t save progress. I thought it had something to do with where I just bought a refurbished 360 that my Microsoft account was just acting funny since it’s a new Xbox. I am convinced now that it’s not the case. I’ve tried everywhere from clearing the system cache, to installing the game to the hardrive, to even upping the security with my account. Nothing seems to work.
*On a side note*
I am getting a message pretaining to data sharing every time I start up the Xbox almost like it doesn’t remember that it’s already prompted me with this message.
I am also getting the occasional message: “You last played on another console” message.
These two messages is what led me to believe it was a problem with my account. Yet, I’ve checked for any security breaches and didn’t have any. I just assumed it was where I bought a new Xbox and my account doesn’t recognize that this is my primary Xbox. But this could and probably is, completely irrelevant to why reach is acting up. But more information on a topic the better I guess.