The Game-Breaking Scarecrow Save Glitch

So I've just lost all my 100% save game file due to some ridiculous save glitch which took me back to 50% fighting Scarecrow on the rooftop. (So much for a AAA-rated game then!)

Anyway, it happened as I was halfway through Season of Infamy and downloading some Challenge packs - does anyone know if this is all just a random bug that can strike any time or did I install a dodgy pack that effed the game up somehow?

I don't want to play this again when my progress can seemingly be wiped out at any time. I really was enjoying SOI but I guess I have to complete the game again before that unlocks which sucks but thats assuming the game lets me get that far!

Cant believe Rocksteady put out a product with such a game-breaking bug. Something similar happened in Origins where for my New Game+ it didn't generate the gadget I need to progress so I was stuck but that game was notoriously buggy and rushed so I accepted that begrudgingly.

But this is a Rocksteady product and AAA-test QA'd game - I accepted a few camera-freezes and the odd falling through the map during various levels but a bug that destroys your save file is absolutely unacceptable and ruins the prospect of further playthroughs.

Anyone experience this glitch or know the cause of it? Can I get around it? (The RB backup thing was useless as it took me back to a 41% save file!!)