Now that we have established that Windows 8 has added a manual TRIM option that it has paired with the HDD defragment feature, together called Optimize, we can move on.
Parrot1553, everyone is not aware of the Windows 8 SSD optimize feature, since all the focus is on the missing Start menu, and anything considered "bad" by the 8-haters.
Questions for you, is your PC on 24/7? If not, the optimize is no doubt a scheduled task as the automatic HDD defragment option is (not that you can tell by the limited configuration it has), which is usually assigned to an assumed time of non-activity of the PC, meaning 2AM or a similar time. If the PC is off at that time, it will not happen, and will not be made up for when the PC is on. It runs only at the scheduled time.
Did you clear your BIOS/CMOS recently? If so, I think that will reset the last optimization time to Never, as Windows interprets the BIOS clear as inserting new drives, or at least starting over with drive letters, etc. Since it can't sort that out even if the drives were not changed, it resets the time to Never.
Edited by parsec - 3/7/14 at 8:12pm