I have an 3TB external HDD with 2 partitions, one of them is 1TB dedicated to time machine (encrypted).
It works perfectly, but whenever I unmount the partitions (by using right click, Eject via finder, which offers the option to "Eject All" partitions of this drive).
When I plug the drive back in, the non-encrypted non-time-machine partition mounts fine automatically, but not the (encrypted) time machine one.
Trying to mount via the Disk Utility app yield the following error:
com.apple.DiskManagement.disenter error -119930868.)
Trying to mount via Terminal by running
$> diskutil coreStorage unlockVolume GUID first to unlock the drive, then mounting that partition via
$> diskutil mount GUID does not work either.
$> diskutil list will just hand indefinitely, and when this happens even shutting down does not work (I guess macOS is waiting for something).
The only workaround I have is too reboot the mac; so that makes me think that it is not an issue with my drive.
Note: The disk is not plugged in directly, but through a thunberbolt3 dock (Caldigit TS3+).