The status that you refer to as ‘released’ and buttons referred to as ‘release’ have been replaced with: Status: Submitted Button: Submit.
If there is still that status present in your tables, it is possible that this was an upgraded instance from way back`? Especially if these timesheets showing the status were frozen prior to the upgrade and change of the status.
This is documented in PPM 7.0 Time Management User and / or Configuration Guide. In PPM 7.1, a product enhancement was also raised to change the Actual Time Summary Report option from ‘include unreleased time sheets’ to ‘include unsubmitted time sheets’.
HOpe this helps. If so, please 'solve' this thread.