I assume heroic event chain is the taking choices and growing your faction leader. Such as what to do with your bird, first fight with Romans, story about Ceasars etc....
I'd done four of them and seen epilogue of these events.(Garlic, Gothi, Sassanids, Palmyra) But loremaster achievement is firmly stable not showing any progress.
Attached savefile is the proof of it. Autoresolve the battle(result does not matter) and `wait for a new turn. Epilogue will popup but progress of the achievement does not go up.
Is there whole new event for this achievement or is it just a bug?
I've checked with several other people and non of them had gain achievement progress.