my SanDisk Ultra Plus SDSSDHP-256G-G26 NOT supported by SanDisk SSD Dashboard?

Hello,

in that case you will need to check if the drive in the device manager is detected as a SCSI drive. If that is the case then thats why the dashboard cannot see the drive because of the motherboard controller.

Also its not true that Sandisk does not suppor the Ultra Plus drive, you can still contact the support for this product and even receive a replacement if it fails within the warranty period.