This idea has been merged into another idea. To comment or vote on this idea, please visit T-I-271 Add jira custom field to tempo report.
We actually use 1h Timesheet gadget to help overcome this limitation. With Tempo's the purchase of this plugin. It would make sense to allow this in the base reports in Tempo.
Even if this was a configurable setting in Tempos core. such as Allow Grouping by Additional fields and maybe limit the number to only 3 Additional fields to group by so help with indexing and Data constraints. I understand that the worklog in jira's core does not contain this data and it would require additional joining of data to report on Custom field values. However you already currently allow the inclusion of additional fields in the Export and Servlet functions for this data.
|Tempo Products||Tempo Timesheets, Tempo Reports|