The drive is running APFS which only a Mac running a newer version of MacOS can access.
Your config won’t work as a MacPro 3.1 highest supported OS is OS-X is El Capitan (10.11.6) which only supports HFS+ volumes. You need to be running Mojave or newer.
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Giving your testing the OWC SSD won’t play in the PCIe adapter you have. Sorry😩
The drive is running APFS which only a Mac running a newer version of MacOS can access.
Your config won’t work as a MacPro 3.1 highest supported OS is OS-X is El Capitan (10.11.6) which only supports HFS+ volumes. You need to be running Mojave or newer.