If there's a problem while uploading a rule assignment sheet to a project, you'll see an error. Select the error message you're seeing and follow the troubleshooting steps to solve your issue.
'General error'
If you're using Google Sheets, share view access with the service email provided so that Ads Creative Studio can copy the variants. The email address is unique for your Ads Creative Studio account, but it will end with @partnercontent.gserviceaccount.com.
Make sure the spreadsheet has Variant Id, Variant Name and Rule Id column headers.
If you've checked all of these issues and still can't upload, it may be a problem with Ads Creative Studio. Try waiting a few minutes, then upload again. If it's still not working, contact support.
'Unknown rule ID'
Make sure the rule IDs match the rule IDs in the project you're uploading to.