I had a similar problem with one of my 256GB Ultra Plus SSDs. Right after a firmware upgrade, my drive was detected by Windows as only 50GB, and without any volume!
Although I had made a backup of my data before the upgrade, I was not happy about my drive not functioning properly. It was all the more frustrating that DashBoard had nothing wrong to report about my drive, except the size. Looking at the details section of DashBoard, and comparing with another 256GB Ultra Plus, I noticed that the only difference (except the serial number) was a much lower “Max LBA” value.
In despair, I searched for a way to modify that “Max LBA” value, and discovered the HDAT2 utility. I tried its “Set Max Address” feature, rebooted, and… Tadaaa, my volume was back with all my data! And of course, the reported size was back to normal. Since then, that drive has been flawless.
