SanDisk 4TB Extreme Portable SSD

I bought the drive to archive a bunch of photos I had previously archived on HDDs. I wanted the speed and reliability boost. I reformatted the drive in my Mac, and then started copying files from my HDD to the new SSD. I encountered a problem where the SSD would spontaneously demount. I would get two error messages: one scolding me for unplugging the drive without ejecting it first, and the other telling me that file <file name> couldn't be copied because the name was too long, or it contained improper characters, neither of which was true. I determined that the files would copy just fine to iCloud. I thought maybe I could then copy the files from iCloud to the SSD, but no luck. I then tried copying the files to a smaller-capacity SSD I had around (different brand), and they worked just fine. I then tried copying them from the other SSD to the SanDisk, and the same crash occurred. I have tried different ports on the Mac, to no avail. When I connect my HDD and the SanDisk SSD to my laptop, the copying works. So the problem seems to be some sort of incompatibility between my Mac Studio and the SanDisk SSD. I am returning the SanDisk SSDs and buying a different brand. I'm wishing for better luck this time after spending several days wrestling with this problem. I'm giving the device a three-star rating on the assumption that it will probably work fine in other situations.