An empty string in the title flag assigns it a default title of 'A'.

[vazonik]

Expected behaviour

The default value is assigned when title is undefined/null/false etc. In case of an empty string, a flag without a label is displayed.

Actual behaviour

An empty string in the title flag assigns it a default title of 'A'.

Live demo with steps to reproduce

https://jsfiddle.net/BlackLabel/dv0yae9z/

Product version

Highcharts v11.3.0

Workaround

Instead of an empty string, pass a string with a space:
https://jsfiddle.net/BlackLabel/7zs9op41/