The answer that worked for me is what drmwho noted above: quote I found some suggestions on the LaCie support site. Some Seagate and LaCie software use a kernel extension (kext). Apple  silicon Macs require that users change the security settings to ‘Reduced Security’ for the software to function properly. To change the level of security on your startup disk: Shut down the Mac Press and hold the power button until you see “Loading startup options” Click Options Click Continue If asked, select a user Click Next Enter password for admin account In the menu bar at the top, Select Utilities Startup Security Utility Select the startup disk If the disk is encrypted, Click Unlock Enter Password Click Unlock Click Security Policy Select Reduced Security Put a check next to “Allow user management of kernel extensions from identified developers” Click OK Enter admin password click OK Once changes are applied, click the Apple icon and Restart *********** Once you adjust startup security, restart and reconnect the drive, it should work. It has to do with letting the drive's software install a kext so it can mount, as I understand it. Good Luck! I struggled and cursed Apple's lack of info on this, finally succeeded. I also found Glenn Fleishman's "Take Control of Your M-Series Mac" very helpful, although he does not specifically address this as a fix for hard drives not mounting. His section on the startup security settings gave me confidence that this was a real, safe thing to do (not just a drive manufacturer hack). Lots of other great M1 info also. Once I did this, the drive mounted and showed up in Disk Utility, which it would not do before. Hooray!

Hi Artyom - Your code here and in Dropbox was very helpful. I am trying to put a video material on an external USDZ object that I have found online and converted. But the material does not show up (the video plays - I can hear it) and I suspect that it is a faulty UV or normal map. I have found code that works with someone else's USDZ created in Blender. I am trying to simulate a planetarium, projecting into the underside of a hemisphere. I have tried every culling setting in Xcode. Do you have any ideas on what I should try now? Thanks!