Apple recently revealed a bug that has been automatically dismounting internal SATA drives off the New Mac Pro.
In a new support document, Apple said that certain internal SATA drive models might unexpectedly disconnect from the Mac Pro when the machine wakes from sleep. The bug might occur when the user sets the Mac to sleep or when it auto-sleeps. The document further iterated that a message, ‘your disk was not ejected properly’ indicates that the bug happened and that the Mac should be restarted to connect the drive again.
Apple did not disclose which models affect the bug, and made mention that they’re aware of the issue. The company intends to add a fix in upcoming macOS updates and promises more information in the future. To prevent the bug from happening, Apple recommends turning off the option ‘prevent automatic sleeping when the display is off’ in the System Settings.