I just got through the majority of Act One of Found Of Durotar on classic mode, almost without a hitch. When attempting to leave the Echo Isles, instead of loading up Durotar to go speak to Thrall to start act 2 the whole campaign restarts from the beginning of act 1. Ive tried restarting the game, reverting to an earlier save state, playing the whole campaign again up to that point, even uninstalling and reinstalling and nothing.
↑My reply to other players with similar problem might help. It is recommended to read it first.
Where is that “earlier save state” saved? Echo Isles or main-map?
Even you “playing the whole campaign again”, but if you still deleted some related or all “OrcX01” save(s), then I’m afraid the “restart” will happen again.