When using map2scenario to for example add in ores from a new mod you just installed without having to regenerate a new map, all current placed factories will be un-enterable and will crash the game when you try to remove them.
Removing them pre-map2scenario and keeping them in inventory resets the contents and sets their health to 1/5000. I managed to work around it by saving the insides of my factories on blueprints, removing the factories and then using map2scenario.

Not sure if this was posted before but I just thought I'd let you know