Chosen Solution
I’ve installed a new 1TB OWC Aura Pro X2 SSD in my 2013 Mac Pro - I’m running Catalina and formatted the SSD with APFS. It’s working pretty well aside from some odd issues. When I boot with the option key to run Bootcamp I will often get a chime and then nothing at all, just a blank screen. I then have to force a shutdown and try again. Usually on the second or third try I’m presented with the Startup Manager screen which shows two external disks - one is “Aura Pro X2” and the other is “EFI Boot”. Obviously these are both on the internal SSD and usually are labeled as “MacOS” and “Bootcamp” or similar. So I get the feeling something is not quite right. Has anyone had this issue with their OWC SSDs?
Similar issue on a MacPro 2009 using a PCI adapter card with an OWC 2.5” SSD mounted to it. It showed as an external drive. OWC has a page of hard drive icons, so I changed it to look like what I am running. On not booting correctly, go into system Preferences > Startup Disk > unlock it > select the drive you want to boot from. See if this solves it.
