The installer won't run on this drive, complaining that that it's missing a firmware partition. I am now trying to upgrade to High Sierra. Everything has worked fine up to now, although the OS still recognizes the SSD as an 'external' drive.
Last year I replaced the Mac's internal 500GB SSD with a OWC Aura 1TB SSD. I have an early 2015 Macbook Pro running Mac OS Yosemite.
