...
Please note, if Restricted Groups setting is set in app configuration, current user can only see or set rates for users in groups, the same for the current user and those selected in Restricted Groups. I.e. if jira-developers group is selected in Restricted Groups, and current user is member of that group, then he can see only users that are also members of that group.
Note, Cost Report is not available on in Timesheet Reports and Gadgets Cloud and Time Reports Server/Cloud., but it is available on there is Worklog Clost additional field in Timesheet Reports and Gadgets Cloud and Time Reports Server/Cloudfor Jira Server, see https://www.primetimesheet.net/wiki/Tips_and_Tricks.html#Cost_report_based_on_the_timesheet_information.