Cannot unselect selected value in custom issue field created by dynamic modules api

Hallo all,
I created one custom issue field with type single_select via dynamic modules api (see here), populate it with options, select one of the options and then when trying to deselect/unselect it seems ok visually but when I refresh the page issue field is still selected. Also jira:issue_updated is not getting triggered when the issue field is deselected. Is this wanted behaviour or bug?

Thank you in advance for help!
Best regards,
Endi