Changing field descriptions in "Field Configurations" for custom fields does not work

To change the field description of a entry field individuell for different projects the standard way is to change the field description in a project related field configuration (I did so for the standard field 'Description'). But I have no chance to do this fo a self created custom field (in this trial for a single select field type). When I change the field description in a specific field configuration, the description then changes also in all other exisiting field descriptions and therefore the changed desciption is displayed in ALL projects and not only in the specific project.

A cross-check in the other field configurations confirmed my initial assumption. As already mentioned above it works for the JIRA standard fields 'Description' and 'Environment' but not for the custom fields. I hope this is just an issue and not the default behavior in JIRA.