Mac OS Sequoia not recognizing USB Flash Drives

Which setting is that? I'm not finding anything that looks like that in Settings.

Edit: It looks like maybe you can only see that setting on laptops; I don't see it on my Studio. If your Mac asks you to allow an accessory to connect - Apple Support

OTOH, on my new M4 Studio I have not yet had any issues with my Garmin failing to connect. Rather an expensive solution to that problem but I'll take it.

15.1.1 doesn't solve the problem.

My case : Mac Mini M4 / Os 15.1.1 / OS updated at startup (new machine)

1. OK : The USB HUB of my Benq PD2705Q monitor connected to rear Thunderboldt/USB connectors with a USB-C/ USB-2 type B2 cable permit the connection of all my USB Flash Drives and other USB accessories (cards reader etc.). This Benq USB HUB is identified by System Information as : 5-Port USB 2.1 Hub, Provider Realtek Semiconductor Corp
2. Not OK : Whether connected on the front or rear USB-C Port, my StarTech Hub (USB-C to 3 x USB-A + 1 USB-C) identified as USB2.0 Hub with Genesys Logic ship has a completely random operation.
3. Not OK : Other Startech products (i.e. USB-C to SATA adaptors) do not work directly connected to Mac USB Ports but there equivalents (USB-A to SATA adaptors) works perfectly on the Benq USB Hub...

Remarks :

1. In case of Benq Hub, System informations give the number of ports, ports are USB 2.1, ship are Realtek
2. In case of Startech Hub, System informations do not give the number of ports, ports are USB 2.0, ship are Genesys Logic

Hey everyone,

I recently encountered a strange issue where my Mac M1 running Sequoia 15.2 suddenly stopped recognizing my Sandisk USB external drive.

Background:

• My external drive has both built-in USB-A and USB-C ports. Courtesy SANDISK USB A on one side USB C on another side.
• I had a Type C to Type A extension cable lying around just in case
• I had been connecting External Drive to the Type-C port on the back of my iMac without any issues.
• The problem started after I connected my iPad to the iMac.
• I initially suspected the drive had crashed, but it worked fine when connected to my MacBook Air M3.
• Command-line tools mentioned in forum didn't work.
• System Report however showed SANDISK External Drive information. (System Report is in App Launchpad with Disk Utility)

The Solution:

After some troubleshooting and watching Youtube, I discovered the issue:

• Connect the drive using the Type-A port instead of Type-C.
• Use the extension cable Type-C to Type-A adapter to plugin SANDISK Type A side (remember I said i had two--back to back).

This simple workaround resolved the issue for me.

Possible Explanation:

I suspect this might be related to Apple's transition to a more USB-C-centric ecosystem, potentially influenced by EU regulations. It seems like some USB-C devices might have compatibility issues with certain configurations.

If this solution works for you, please leave a comment and let others know!

Disclaimer: This is just one user's experience. Your mileage may vary.

I hope this helps!

PS: This post reflects the user's experience and potential explanation. It may not be the definitive cause or solution for all users.

Disclaimer: This post expresses the user's opinion and may not reflect official Apple policies or statements.

Closely related issue ... when re-booting, my external drive will not auto-mount.

2019 iMac 27-inch; Sequoia 15.0

Any thread dedicated to this issue?

They appear greyed out and will not mount although Time Machine is recognised.

Even using Apple connector does not work.

They ARE encrypted. And strangely, they actually automount about 10% of the time! Intermittent issue! Hard to debug!

My external Hard drive is no longer showing as I updated to Sequoia , even my IPhone 15pro doesn’t even show up anymore. This is really frustrating.

A Store N Go very old USB is recognised after installation of Sequoia

The external is not recognized the external does not show at all in Disk Utility. That is what is happening.

👍

Updated to Mac OS 15.0.1 still does not fix this issue

Have any of the apple support team seen this post? this is pretty critical.

I downloaded the Sequoia 15.0.1 update that was, I believe, was posted today which has resolved my inability to use FAT32 formatted USB flash drives.

I reported the matter to MacOS Feedback, but Apple hasn't bothered to respond.

Same issue here.

Disk has been in regular use with no issues until updgrade. Also works fine on second older imac also running sequoia

Disk shows in disk util but is greyed out and will not allow me to mount it

I tried mounting the disk using terminal but it gives me the following error:

mount: /Volumes/drive6s1: invalid file system.

Sys info for disk...



Re-formating as suggested in other threads does not work...