Do you carry over XP from one mission to another of the Kickstarter Campaigns (Kickstarter Campaign, Researching Spook Central and The Sedgewick Scramble)?
The base/retail campaigns all specify you carry over XP, but these ones do not.
That's an interesting thing to notice... I just assumed that you carried over XP for all scenarios within a campaign, since they do tend to get harder as you go along, and the first one or two are generally full of ghosts to "farm" XP from...
I would continue to assume that you carry over XP for all campaign scenarios. I suppose if you'd like a more difficult game, you can reset your XP each mission, but I imagine it would be tough to beat the final scenarios without your level 5 abilities.