Summary

On JIRA Cloud, when the sysadmin user is member of a given group, and this given group is used as a parameter of the membersOf("") function, the whole JQL doesn't work and return an error:

A value provided by the function 'membersOf' is invalid for the field 'assignee'.

Steps to Reproduce

1. Add the sysadmin user to a group (it can be any group)
2. Go to the issue navigator advanced search and use the function as follows:

   assignee was in membersOf("<group-sysadmin-is-member>")

Expected Results

JQL returns the issues according to the JQL

Actual Results

No issues are return, and the JQL fails with the error

A value provided by the function 'membersOf' is invalid for the field 'assignee'.

Workaround

Contact support at https://support.atlassian.com and ask them to remove the sysadmin user from this group.