Confirm if users are in Management Reporter, first let everyone know to log out of just Management Reporter (users don’t have to be logged out of GP). Then in the Management Reporter Report Designer, you can go to Tools > Checked Out Items, tick ‘Show items from all users’ and this will show if any users have any reports open. The MR Report Designer would be on the machine that the users connect to get to GP.
Rebuilding Your Management Reporter Data Mart - Encore Business Solutions