download the second-to-last save
you're not alone) everyone needs to check the user mods folder and make sure they're consistent. In reality, the map has already been generated - you can both remove all files from the user mods folder, which will eliminate the possibility of an error due to a date mismatch.
Very rarely... but it seems that someone had a situation where the map was copied into the maps folder as a copy... there should only be one with that name.

But it seems you have a different problem? Is it impossible to load any save, not mentioning an error, but that the name is not mentioned?
Try loading each save individually. If someone reports that the name is not mentioned... load the previous one. Again? Well... did you only make named saves or also autosaves? They might have been lost if the person who saved them played a bunch more games in the meantime, without putting the necessary ones in a separate folder. If that's the case and the second person doesn't have them either... that's it).