Previously we were able to get all fields for a particular project (categorized by issueTypes) through this API :
/rest/api/2/issue/createmeta?projectKeys=SC&expand=projects.issuetypes.fields
We need something similar (this seems to be deprecated) and this particular API didn't return me the "Assignee" field despite the issue having an assignee field.
We have ASSIGN_ISSUES access: