Well, sorry to stir this up once more, but I recently (as in basically last week-end), started to experience this issue, with the whole of Whiterun suddenly turning on me for no reason whatsoever and cutting me down to pieces. A simple load from the last auto save brings me back to the point before it happens and then it doesn't happen on the second time around, proving that's a random occurene in the AI. I'm not specifically asking for a solution, just pointing out, for the sake of those still investigating it that I didn't experience the bug until I had installed Warzone - Civil unrest on the Special Edition. My guess is that the various random battles, combined with Open Cities, cause the towns to suddenly go nuts and tag you as hostile. No idea how, where, or if there's a fix, but I thought I'd share this, to help those who have the wits and skills to find out what's wrong with the mods.