Just a quick note to share some insight gained last week through an unfortunate discovery.
Many support articles recommend rebuilding the Management Reporter Data Mart connection as a way to troubleshoot reporting issues. I have done this numerous times for many of our clients without any known issues.
Last week, after performing a routine rebuild of the Data Mart, our client noticed that the transaction drilldown was no longer available for past reports saved in the Report Library. Any new reports generated had the transaction detail, but the detail for all old reports (prior to the rebuild) was lost. After discussing the issue with Microsoft, we discovered that there is no way to recover this detail without regenerating the reports.
Be sure to consider the impact of rebuilding the Data Mart connection, or store your past reports outside the Report library to avoid losing this detail.