MY PASSPORT only mounts on new macbook

Brand new 2TB My Passbook. mounts fine on my Macbook Pro, but when plugged into any number of USB ports of my older Mac Pro running 10.11.6, it doesn’t mount. Tried reformatting the drive from my older mac. It seemed to mount fine then. Plugged it into my macbook pro and it showed up, but when I brought it back to the older mac, the same thing happened. It shows up in Disk Utility and System Profiler

Not sure if this matters but I’ve installed Catalina on the drive, which is incompatible with the older mac, but shouldn’t the drive itself still mount?

Hello,

Please refer to the following KBA article: Cannot Find My WD Drive on Windows or macOS