External SSD Mounting Issue On M2 MacBook Air - Strange One

mpconnick wrote:

When attached to the MacBook Air in question, the SSDs DO appear in the System Information app's USB section under USB 3.1 Bus. They DON'T appear in Disk Utility or otherwise mount.

Within Disk Utility click "View" and select "Show All Devices". Do the physical drives now appear on the left pane of Disk Utility? Apple tries to hide everything from users in an attempt to keep things simple, but it just ultimately causes even more problems & confusion.

I have tried reinstalling Ventura over top of my existing install. That did not work. I have erased my internal disk and reinstalled Ventura completely. That did not work.

Reinstalling macOS over top of itself doesn't really do much these days since the OS is located on a read-only signed & sealed volume so the OS no longer becomes corrupt. The only part of the macOS system which is vulnerable are the custom configurations made to the system which may not be replaced (I'm not sure what happens).

The one change, however, is that upon connecting the SSDs for the first time I was asked to allow them to connect. I clicked Allow, but it made no difference.

I would configure the "Allow accessories to connect" in the Security & Privacy System Settings to "always when unlocked" so that you don't accidentally miss the prompt....especially when troubleshooting.

I have a Satechi USB C Pro Hub Slim that connects directly to the side of the MacBook Air. It connects using both USB C ports and does not have any external power.

The hub has one USB 4 port. If I connect an SSD to that using USB C to USB C cable, it DOESN'T• work.

This is because the USB4 port is only meant for power or for connecting an external display. You must always read all the technical specifications for USB-C ports on any product to understand what each one supports. The whole USB-C connector specification is a hot & confusing mess. You cannot assume anything. If you don't see anything specific, then assume the USB-C port only supports the lowest protocol & features.

Keep in mind that in the two scenarios where it does work with the hub, the data is still ultimately traveling through the MacBook Air's USB C ports that fail when doing a direct connect.

Try modifying the Security & Privacy System Setting I mentioned earlier to "always allow when unlocked".

Disconnect all other external devices in case one of them is causing a problem.

What file system is used on those external drives? And what computer & OS was used to partition & format them?

Are the external drives encrypted?

FYI, you may want to check the WD/SanDisk support site to see if either SSD has any firmware updates available. This is especially important if you have the version 2 Sandisk Extreme Pro SSD which has a major issue that can cause data loss (WD/Sandisk are too embarrassed to admit the issue and only acknowledge a drive disconnect issue):

https://arstechnica.com/gadgets/2023/05/sandisk-extreme-ssds-keep-abruptly-failing-firmware-fix-for-only-some-promised/

https://arstechnica.com/gadgets/2023/08/sandisk-extreme-ssds-are-still-wiping-data-after-firmware-fix-users-say/

You've done a fair amount of troubleshooting already, that's for sure!

It's not clear, though, in your description, if either of those drives mount when connected directly to your Mac? It appears maybe all your troubleshooting had those drives connected to the hub?

mpconnick wrote:

Regarding reinstalling the OS over itself, I'm aware of that but things can still go wrong. And when I walked into the Apple Store the day after making this post, that's the first thing the "Genius" wanted to do. More on that visit coming in a separate reply to the thread.

Apple usually insists on a clean install of macOS for testing (requires erasing the disk first), but many Apple techs really don't know what they are doing. It is best to test the clean install before any third party apps are installed and before restoring from a backup since both of these things could bring back the problem.