Sequoia 15.0 bugs - external hard drives

When it comes to external drives I have trouble mounting, trouble ejecting, and when I'm trying to open a folder with too many files MacOS just says "Loading" for about 10-15 minutes before it even opens the folder. To clarify, the drive works fine on Windows machines so it's clearly a MacOS issue. My best guess is they added or modified some type of cache so now the drive constantly has to access that cache before mounting, before ejecting, and before populating any folder/directory.

I feel your pain. Since, at least, the initial release of macOS Sonoma, I have had nothing but trouble keeping access to my SanDisk USB 3.0 (USB-C) drive. If Time Machine isn’t failing, Disk Utility is.

There have been countless complaints about connection issues (bugs and possible decagon flaws) in macOS with regards to USB-C drives for years now.

Apple appears either incapable or unconcerned about the myriad of issues with macOS and external USB-C devices.

I think there's an issue with Sequoia, power management, and micro-B type USB connectors. I tried plugging the drive into a micro-B USB powered hub and it was mounting but was still randomly unmounting unexpectedly. Plugged into a non-powered USB-C hub and no issues so far.

Wish this was a fix, but it's not. (Plus, the instructions for resetting the SMC controller on Intel-based desktops differ from what's posted.)

This bug, which seems to have been around at least since Sonoma, manifests differently across machines, is not confined to any one type of connection/cable and, unfortunately for the purposes of escalation, isn't a global issue.

It is, however, persistent and a major pain. (Note: after 15.3.1, my external drives are now all working, but two of the three—the USB-C drives—will not unmount.)

Yes, it was not the fix. I’ve only had issues with large (5TB) portable drives, Seagate and WD connected via a powered USB hub. Occasionally, the drive disappears especially after a reboot or startup if my Mac Mini M4 Pro has been shut down for some reason. After trialling the SMC and NVRAM fix, the external drive just didn’t show up as connected. My only way to get the drive to reconnect has been to plug the drive into my old 2014 Asus Windows Laptop running W10 and running the Check Disk tool. It always shows there are errors but fixes them and then when I replug back into my Mac Mini, it shows straight away.

What is a powered monitor or USB hub? I’m having the same problem with my sequoia update since the end of February 2025 I cannot use my external drives without them freezing or acting weird turning off and on.

Tinx_Lvs_JC wrote: "...Apple - please fix this bug!..."

Apple isn't here — use this form:

Feedback - macOS - Apple

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carlamm wrote: "...APPLE DO SOMETHING!"

carlamm ~ Apple isn't here in these user-to-user communities. Instead:

Feedback - macOS - Apple

Contact - Official Apple Support

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SimplyArt wrote: "Apple! You have been my "rock" (...) Apple, please give us..."

SimplyArt ~ Apple isn't here in these user-to-user communities. Use this form:

Feedback - macOS - Apple

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GizinUK wrote: "...Apple sort this as data loss is a critical issue."

GizinUK ~ Although Apple administers these user-to-user communities, that doesn't include reading each of thousands of daily posts for possible feedback. However, you can tell Apple to "sort this" here:

Feedback - macOS - Apple

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I have same problem with my MacBook Air M1. I recently upgraded to Sequoia and now I get Lacie Hard disk cannot be found.

Same problem, exFAT not working normally, super slow responses

Perfect. I nearly went and bought another drive. Switching it for a hub to the socket at the rear of the Mac sorted my problem. Thanks.

I am trying to find this - when I search for it - it points to privacy and integrity, but it is not there. Why did I do this. I have all my files externally

I just updated March 2025 and I have all sorts of problems