I have encountered the same issue on two different PCs after upgrading to the RST 12.6 driver. The problem goes away after the storage driver is rolled back to RST 12.5.
It appears the 12.6 driver has changed the way storage devices are reported to the OS. I'm not sure if this was intentional or a bug, but I agree the Intel SSD Toolbox has fallen behind and a new revision is needed.
Thank you for posting.
Scan80269, you are correct in regards of your first statement; the drive is probably detected as SCSI (Hardware ID) in device manager, this also happens when the SATA controller is set to RAID or is in fact a native RAID controller. However, this is not an issue with the Intel® SSD Toolbox specifically.
Since the way the drive is detected changed in device manager, the SATA controller is not able to translate the TRIM command to the drive. In this case we recommend rolling back Intel® RST and report the issue to the Intel® Chipset Support Communities.