Re: Custom content just won't work?
Okay, so I fixed it - even though I don't fully understand how/why it started working again:
My Documents folder on my Mac was synced to iCloud. I renamed the EA folder to EA.nosync, and waited for the file to be removed from iCloud. I then relaunched the game and enabled script/content mods. This created an entirely new folder structure which synced to iCloud but as if it were a new install.
I then copied over my mods to the new mods folder in the new structure. Once that was done, I deleted the EA.nosync folder. I lost all my saved households, however, all the content does now work - which was what I wanted!