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So whenever I encounter a group of enemies, they seem to only pursue me up until a short distance (sometimes refusing to go more than 10 metres away from their initial standing point).

This is making it very hard for me to lay traps and use them effectively. Are they meant to be doing this or is it just happening to me? As soon as they hit some invisible threshold, I can usually just stand out of range and spam spells at them - removing all tactical play from combat.