Maybe this has something to do with the Cities Building Update?
Did you agree or disagree to the changes?
But there are also random objects showing up when we agree, like shown in this post.
Let’s hope this gets fixed soon
Unfortunately, when attempting to open it, we found that it’s a split ZIP archive. It seems we’ve only received the .zip file and are missing the accompanying parts (e.g., .z01, .z02, etc.) required to fully extract the contents.
Could you please re-compress the entire save folder into a single, non-split standard .zip file and resend it?
If the file is too large to upload to the forums, you can use Option 2 below: