Dichotic

I had made it through almost everything (Through to 6-5) on Normal, most on Heroic and was working my way through Legendary for the bonus unlocks.

Will I need to redo all my story progress if I do this?

I have started working my way through the Legendary missions in story mode and am part way through 4-1. I had a character facing Longtooth as a summon on an enchanter and selected the summon monster spell than cancelled it and went with Sign of Wrath instead. After rolling the dice a monster was summoned anyway and a fight occured. Then it came up with the option to evade or continue from sign of wrath. I chose continue and couldn't go any further. I restarted the game, went back in to story mode and again it comes up with the option to evade or continue. No matter which one I choose I cannot go any further or select anything else. Not even the vault or settings menu (although it makes the sound when I select those buttons). Because I cannot select the settings cog I cannot even forfeit the mission to try again. I have tried clearing the cache, but have not cleared the game data yet as I am afraid I will loose my game progress. What are my options to retain my progress and be able to continue playing story mode?