Mac OS Sequoia not recognizing USB Flash Drives

Strange, all USB drives show up fine here in Sequoia 15.2

Are you running any VPN, Anti-Virus, or Cleaning apps?

We need to see what all is running, a report from this will not display any personal info...

Using EtreCheck - Apple Community

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Thanks for Old Toad’s etrecheck instructions…

Slow iMac 2017 - Apple Community

Can you try shutting down the computer (not just sleeping it) connecting the drive to the usb port, making sure the drive is powered on if it has separate power, and then turn the computer on with it connected?

I’ve been able to kick this problem by doing this and then just have all the usb drives that were giving me trouble mount reliably afterwards.

i had to buy a usb c adapter and plugged my thumb drive into it and thumb drive worked with this metheod

I've found that my USB stick (Type A Connector) drives do not mount, however if i attach a Type-C adapter to it, then it mounts. Anyone have any answers as to why this is happening?

This is driving me nuts. After initially updating to Sequoia yesterday on my M2 Macbook Pro, my USB Dongle device initially mounted fine, automatically. Today it won't mount automatically.

It's recognized, in that I can see the device in Disk Utility. However, the button to mount in Disk Utility does not work.

I can only seem to mount the device through Terminal by performing the following steps:

1) Call up the disk utility list

diskutil list

2) Find the DriveIdentifier for the USB device in the list

3) Create a Volume to mount the device:

sudo mkdir /Volumes/YourVolumeName

4)Mount the device to this volume

sudo mount -t msdos /dev/DriveIdentifier /Volumes/YourVolumeName.

It's a USB2.0 device plugged into an apple USB-C multiport adaptor, the drive is FAT32 formatted. Allow Accessories to connect is set to Always. Finder settings are on to show External Disks in Locations on the sidebar.

And the kicker: This same USB device mounts automatically w/o issue on my M1 Mac Studio updated to Sequoia the same day! What gives Apple? Please address this issue ASAP. We should not have to run terminal commands to mount USB drives. This is not a viable work around for users who do not have admin permissions. Thank you.

So this is interesting. I found a discussion post from 2011 where someone said to reboot the computer with the usb drive connected and that... got it to mount on my 2019 5k iMac. in fact, I was able to eject and reinsert my FAT32 formatted thumb drive and it mounted successfully the second time too. I'm looking at it right now.

Fat32 formatted disk partitions do not mo… - Apple Community

trying to get used to a new MacBook.. Sequoia, same problem.

however.. click on - about this mac:: system report:: hardware/USB - and there it is... click on it and it appeared in finder?

As recommended, restarted the MacBook, pop up asking if I trust the usb drive- all seems ok? Just about to try another one...

I saw upthread someone had gotten their device to work after leaving it connected for a long time, so I left my Garmin plugged into my Mac overnight. The next morning it was still not connected but after unplugging it & plugging it in again it connected & Garmin Express was able to see it. It's continued to work through several disconnections & reconnections - it's slow to mount (takes 20-30 seconds) but so far it's working.

Apple got me through this one. In my case my Studio M3U wasn’t recognizing my G-Raid DEXT Driver Installer and my G-Speed SSD Shuttle wasn’t docking.

So this was the solution…Reboot in Recovery. Change your security settings to allow Kernel Extensions. Restart. Go back to system settings. Type Ext. Choose Extensions. Click the i on Driver Extensions. Turn on your Driver Installer. Plug your drive in. Should work!

for me it worked like this (sequoia 15.1)

after connecting the external HDD, i ran in the console the command

diskutil list

after waiting some minutes finally my partitions were listed and mounted.

What helped me was starting the Mac in safe mode and leaving it that way for several hours (overnight) with the USB connected

MJ wrote:

In my case, no the drives really aren't mounted.

I CAN manually mount them using Disk Utility, but that is a pain.

Are they encrypted? I have seen older versions macOS not automatically mount encrypted drives....not even offering to provide a prompt to unlock them. I believe I have even seen the same for un-encrypted USB drives before, but I am not 100% certain. I never had the time to look deeper the issue since were Macs in my organization & the user was not complaining about it....I only noticed it while working on the devices.

Are you connecting these drives directly to the USB-A ports on the Mac Studio but via some dongle in the MacBook? Maybe the difference between the two has to do with that dongle in the middle? Which dongle?

Would it work if connected directly, using a simple USB-A/USB-C adapter?

Similar issue. Mac Studio M1 will not mount an XQD card (Formatted in Nikon Camera) and USB flash drives. SD cards in the Mac Studio slot work just fine. All worked smoothly before updating to Sequoia.

All cards and USB's show in Apple System Report with all details. Tried all the reboot etc tricks.

I have been in touch with Apple. Escalated case to OS engineers. Hopefully there will be a solution shortly. Very inconvenient.

UPDATE

Bought the new OWC Express 1M2 and it works at a fantastic rate.

Both read and write are well above 3000mb/s. So it was a defective enclosure of some sort. But rather odd that it worked on all of my older OS X systems...