SSD not seen in Disk Utility but shows it is connected in system report

Hi,

So, from what I know, System Report looks hardware level itself and can tell what is connected; but Disk Utility looks at the drive and format therein. I suspect one of two things:

1. Your SSD maybe flaky (even new ones can be) or
2. You Thunderbolt cable/port/device is either not seated properly or faulty

In the latter case, I would suggest removing the cable and trying a new one (first). If after a fresh reboot of your Mac, connect the drive and see if it mounts. If it does, run Disk Utility's First Aid immediately on it. Depending on what comes back, you may have solved the issue and/or need to move on to other steps.

If the drive comes back with issues that Disk Utility cannot resolve, I would suggest copying the contents of the drive to another drive, and then, reformatting the SSD. Once the drive is reformatted, again test the drive by running Disk Utility's First Aid, once run and no issues remain, eject the drive and disconnect it. Wait a couple of minutes and then connect it again and see if it remounts successfully. If it does, I think you can use it again. If it doesn't though mount, get rid of the SSD and get a replacement.

Disk Utility User Guide: https://support.apple.com/en-ca/guide/disk-utility/welcome/mac

Post back if you've issues or questions.

Cheers,

Anthony

Do you recall how the external drive is formatted? Also, is it formatted Mac APFS or HFS+ with Apple Disk Utility, or are you using "tools" that came with the drive or were downloaded from the manufacturer? If you are using third party drive utilities (which I and others i these forums generally recommend not doing) they could have become out of date with a recent MacOS update and hence stopped working to interact with the drive.

Try booting in Safe Mode, holding down the Shift key (this can take quite a few minutes) until the login screen appears. Does the disk show up now?

Try logging in as a different user, can the drive be seen then? Create a new admin user if necessary to try this. If it can be seen, then something in your original user account has changed or has something installed that is incompatible and that would need to be troubleshot.

When you are in the state where you do not see the drive in Disk Utility but can see that there is a device connected via System Profiler, can you find a process running in Activity Monitor called "fsck_xxxx" where xxxx could be HFS or APFS or something relating to the disk format? Does that fsck process keep running for a while? If it is running, it is automatically trying to repair a disk that it detects a problem with, this could take some hours, and when that occurs the drive is unmounted and might not be visible; you can also choose to kill that process manually in which case the drive should mount in Disk Utility immediately (and on the desktop), but possibly in an uncertain or degraded state. But you could then elect to perform repairs manually with Disk Utility or some other program. Suggest you consider DriveDx for hardware diagnostics only, run the extended (long) test on the problematic drive. Disk Drill or similar recovery software might be able to recover the drive if it is damaged.

Alternatively, try booting into Recovery mode with COMMAND-R held while booting. Then try to examine and repair the external drive with Disk Utility from Recovery.

Have you tried different ports and cables? Also, performing an SMC reset might clear an issue with the ports, although I think the likelihood of that helping is remote, but certainly harmless to try.

Can the drive be detected on another computer?

It is possible a recent Big Sur update broke something. There are a lot of posts on these forums where users are reporting USB drives are no longer working after upgrading to macOS 12.x Monterey. It is possible a Big Sur update may include a change which was included with Monterey. Also last year some USB hard drives also had issues when connected to M1 Macs. It is hard to say when Apple is so secretive and won't tell their users anything about updates or known issues.

Or it may be an issue with the external drive such as a bad cable or a bad drive.

Make sure to connect the drive directly to the Mac since adapters, docks, and hubs may cause problems. If you are connecting the drive directly to the Mac, then try using a powered USB3 hub in case the drive needs more power plus a hub can act as a buffer and filter. Also try connecting the drive to another USB-C port. You can also try rotating the USB-C connector on the drive cable 180 degrees upside down in case the USB-C port is half bad.