I have updated to 2.4, this has resolved the issue. Thank you so much, sorry to have wasted your time!ok, so the file is there. Is it 'blocked'? Right-click it, and choose properties, and make sure it doesn't say anything like "this file came from another computer and is blocked". If it does, click the check box to unblock it. Other than that, I'm stumped.
edit: are you playing on the latest stable base game - v 2.4?
I never think to update to the latest, latest version because of historically losing my saves mid-game, I will definitely try that first next time. Have a nice evening!