Another nail in the coffin for JIRA. This sort of amateurish design (followed by a complete lack of action) is dreadful.

More helpfully, you need to check the customfield table to see what the correct ID is to use:

select id from customfield where cfname = 'Sprint';

e.g. this returned 10005 for us so we used customfield_100005. Many thanks Gregory!

Many thanks for reporting this issue. We see it as a valid feature request however we cannot provide any guidance at this time as to when, or if, we'll be implementing it.

Regards,
JIRA Agile Team

Our team members and our clients have been asking us for this a few times - is this scheduled to be done any time soon?

Thank you

Hi Jason, if you want a quick fix:
I've solved this issue by creating a calculated field, which retrieves the sprint name or ID as you like it, and then you can order by your custom 'Calculated sprint'

free addin:
https://marketplace.atlassian.com/plugins/com.innovalog.jmcf.jira-misc-custom-fields

Use a custom fied: Calculated Number Field

in description enter the formula
<!-- @@Formula: issue.get("customfield_10500").iterator().next().getId() -->

Hi GreenHopper team,

Do you know if this will be looked at in the upcoming releases?

This is a major problem.
We are using sprints as iterations. We really need to be able to sort by sprint, assignee