How are you transferring the file? If you're using an external drive, try using a different cable & different drive, maybe a thumb drive if you have one. Can you connect to OneDrive on the old computer? That is supposed to be one of the benefits - maybe connecting & syncing SimCity to your OneDrive folder on the old computer will make it accessible on the new computer. (Give it time to sync properly before you access it on the new pc)
I'm with you that there's something about this particular region, rather than the usual suspects like antivirus or permissions. I'm honestly running out of ideas. I hope that there's a special character somewhere in that save that is messing with the process, and not any true data corruption.
Let me know how it goes, and in the meantime I'll ask around and see if I can get any new ideas to share.