Sorry if this is a repost but I just finished the Seige scenario in the Campaign on Normal Difficulty and when I went to start the next scenario Achilles' Heel the default difficulty was set to Cakewalk. I've always seen the difficulty remain the same as the last time you played so I almost overlooked it. I reloaded the last saved game in Seige and tried to reproduce it, it was again stuck on Cakewalk. It's not a big bug or anything but someone might accidently play the scenario on Cakewalk difficulty real easily.