Our SanDisk SSD stopped working all of a sudden on our Mac as well. We couldn’t see the drive in Finder and it didn’t work anywhere. We checked Disk Utility on the Mac and it showed a faded SSD name and reported as “Not Mounted”. However, when we connected the same drive to a Windows PC, all the files were intact. I think we could have scanned the drive and been able to Restore it to its default way but we opted to copy the files out, format it and get it to work again.
I have exactly the same problem. Did you happen to resolve it in the end
Just wanted to say THANK YOU, it worked! My 1 TB Sandisk SSD stopped working (maybe that’s the cable? no idea so far). Installing the Disk Drill helped! Thanks!!!
@ bmamukashvili it also worked for me. Thanks. 
Worked for me as well. I had to remove the password on the drive as well, then it formatted and all was good.
I could safe all my files with Disk Drill, but could´t mount the ssd. Not via Disk Drill, not via Terminal, not via Disk Utility…nothing worked.
The only solution that worked was:
I connected the ssd to my phone, formatted it.
First it did not format, tried a second time it succeeded.
Then plugged back to my mac m1 and erased again to APFS and all is good now.
Let´s see how long!
Everyone! Go to Activity Monitor, under Disk tab search for “fsck_****” where **** is whatever your drive type is. Anyways force quit it and you’ll be gucci💋
The firmware update tool is now available.
Connect the Extreme portable SSD to a different USB port on your MacBook Pro. This can help determine if the issue is specific to a particular port.
I purchased a San Disk Extreme Pro Portable SSD Model Number SDSSDE61-1T00, from Costco, November 2022. I have used it multiple times every week since then now it will not mount. I have tried different cables and 3 different MACs. Is there a solution to this problem? Or should I send it to SanDisk for a replacement?
Thanks for the advice but I have tried to connect it to 3 different computers and it will not mount on any of them.
WTF, we are 2024, and yet after buying a new one this week I have the same problem?
Hey, did you ever get a response or find a fix?
I can’t speak to exactly how to fix your SanDisk, though it seems like putting it in a PC did work for me.
But after extensive research, I believe that the underlying problem is actually an Apple rather than a SanDisk issue. Every time my MacBook went to sleep, it would disconnect my SanDisk SSD. Then it would tell me I had not ejected my drive properly, and then I would have to use Disk Utility’s First Aid to fix it so I could see it. I finally found a thread on the Apple forums that explained it.
If this is what is happening to you, someone came up with a homemade fix here: ejectify.app
I have no connection to this person, but the fix seems to be working for me—no more popups about improper disconnects.
I urge everyone to complain to Apple, because this has been going on for years on many brands of external drives and threatens all our data.
Hey! I’m having the same issue with my SanDisk Extreme Portable 500GB. It initially connected fine to my Mac Pro, but then the cable started acting up, and I had to reconnect it multiple times for the drive to appear.
Now, it’s not showing up at all. I’ve tried different cables and even another Mac, but no luck. Any ideas on how to fix this?
Bought a new Type C - Type C Thunderbolt cable and the drive showed up on my MacBook Air M2 2022, I think the problems reside in the cables and fyi stock cable was also failing to connect.
Thank you, I have a new G40 4TB drive that I just loaded up with 1TB of files, and looked good, so i deleted them from MacBook. i ran a cleaner, dumped the trash, backed up the MBP, and went back a reconnected the drive and it wouldn’t mount. I eventually connected to an iMac and it was there with the 1TB of files. Went back to MBP and it wasn’t there. Tried your solution and Voila! it’s all there! Thank you so much for taking your time to post this! It’s been many years since I dabbled in this kind of knowledge, and i never would have found this.
