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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.
Corner case: -1 Hourly Rate in the Cost Report is shown, if Hourly Rates is setup for a group, and current user does not have Browse Users Jira Global Permission.
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Note, Cost Report is available in Timesheet Reports and Gadgets Cloud and Time Reports Server/Cloud., but there is Worklog Clost additional field in Timesheet Reports and Gadgets for Jira Server, see https://www.primetimesheet.net/wiki/Tips_and_Tricks.html#Cost_report_based_on_the_timesheet_information.
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