Hello,
Thanks for contacting us with your question!
This seems to be a bug. Thanks for reporting it! I've created an issue on GitHub, so any updates about this problem you will now receive there:
https://github.com/highcharts/highcharts/issues/17971
As a workaround, I can propose you set the attribute
breadcrumbs.showFullPath to false, but you can expect some other solutions on GitHub.
Demo: https://jsfiddle.net/BlackLabel/d5oyg7hb/
If you have further inquiries, you may reach out to me at any time.
Kind regards