This is a timing issue:
You will see the Workstation column if the reports were executed from the Workstation, you will see a DevTest Portal column if executing from DevTest Portal.
Regression runner should show if executing from Jenkins.
The caveat is, that it takes some time (by default i think it is 60 mins) when data is sent to Enterprise Dashboard. The columns are read from the Enterprise Dashboard database so if there are no data for Workstation ( or data are not send from registry(workstation) to dradis yet) then they wont show up on report.
Regression Runner column only shows up if a report was run from a user with a role of Runtime User.
Test invoke API can return suite information for suites executed by time period: Test Invoke API
The developer says of these counts:
These counts are passed/aborted/failed tests in suites that were executed.
To get statistics about how many suites were executed,
http://localhost:1505/lisa-test-invoke/api/v1/suites/reports?startTime=2018-09-11T00:00:00-0700&endTime=2018-09-26T16:33:00-0000
In the report there is "count" field with the total suites number.