TBH, I’ve never had much luck with XML imports. I’ve been using SQL export/import with very good success. Access phpMyAdmin for the original site and export the entire WP database. Use the defaults for the SQL file format. Pay attention to where the file goes, it varies by host.

On phpMAdmin for the new site, drop all existing WP tables, then import the SQL file from the original site. Do not attempt to log into the new site just yet, unless the URL to reach the site is exactly the same as the old, as when the DNS zone file is edited to point the same domain to a new server.

With a different URL, download and install the Interconnect/IT search and replace tool. Use it to replace all instances of the old URL with the new one. Be sure to use the dry run feature to ensure the search/replace will work as intended. Be sure to delete this tool when finished — its continued presence is a huge security risk.

If you also copy all of the wp-content/ files over, you will have effectively cloned the old site on a new server.

If not, all I can suggest is ensuring the source and target installations are the same versions, including all active plugins and theme, and the DBs have the same charsets.

It’s coming down to either attempting to debug the problem yourself or trying a different XML importer plugin. There appears to be a few possible candidates in the repository. Good luck!