LaCie2 Drive disappeared

The drive may be failing (or may have failed).

In Disk Utility with the drive in its unmounted state, try running Disk First Aid on it. When First Aid is run, the first thing it does is try to unmount the drive.

If First Aid won't run, try manually mounting it in Disk Utility, then try to run Disk First Aid.

Consider downloading DriveDX to look at the physical health of the drive.

Honeybun101 wrote:

Thank you. Ran First Aid and it ‘failed.’ Tried to mount it and got ‘Cound not Mount LaCie2 (con.apple.DiskManagement.disenter error 49244). I’ll look into DriveDX, but I’ve had this drive for a while.

If you have any LaCie drive software/firmware installed for use with this drive, check to make sure it is up to date and compatible with Sonoma.

If that does not apply to you or it is up to date, then I am suspecting that this drive has failed. I would acquire a new drive asap and do an initial backup with it to verify that external drives do work properly and it is this specific one that is not working. Assuming it does work, just continue to use the new drive for backups.