Help please

We have set up a course with certification and re-certification criteria. 

When we run reports the previous course completion dates do not appear in the reports once the re-certification period is active. None of the reports or fields we have found show a list of previous certification completion dates for a course. We know the data is there in Totara because an individual user can look up their previous completion dates from their record of learning certification page. 

This is necessary for auditing and historical data purposes. 

Has anyone found a way to report on all these dates? 

We are using 2.9 and upgrading to TotaraLEARN 12 in the next few months.

Thanks for any advice.