Hi Alex,
Thanks for posting in the community.
For importing XML data in Excel, pleas view the reference: Import XML data and try other ways to import XML data. Check if it helps or not. If the error message still pops on without removing the first line, the issue is likely caused by the XML file itself. Since we have a specific channel Q&A Community coping with fixing XML file, I suggest you post a new thread there for expert help.
Sorry for that our category may have limited resources on checking on the issue further.
Regards,
George