Migration from multiple source urls does not work.

source:
   plugin: url
   data_fetcher_plugin: http
   data_parser_plugin: xml
   urls:
     - private://migration1.xml
     - private://migration2.xml
     - private://migration3.xml

While importing migration through drush commands, all three XML files are migrated. However, when importing from the UI, just the private:/migration1.xml file is migrated and the others are ignored.

Do we have any solution?