I was editing a factory, to reconfigure it to produce the same engine more efficiently, and add a few buildings. Before signing off and paying for the update, I did a manual save while in the screen to configure the factory.
On returning to this save after the additional buildings shut down the production line for way too long, I found I couldn’t reconfigure the factory at all. It says “New factory configurations cannot be created while construction of a previous configuration is underway.” Except, of course, there’s no construction. I am now unable to edit this factory through any menu, with a new engine through the engine project screen, nothing.