LaCie from old computer will not show up on new computer despite same AppleID

My LaCie that I used on my old MacBook Air from 2015 doesn't show up on the new Mac Air that I bought in January. I tried Disk Utility and the command "diskutil list external" in Terminal but it's not showing up there. It only shows up when I go to System Information > Thunderbolt/USB4, but I can't do anything with it. The light is steady on the LaCie itself, and I'm using a brand new adapter for the new computer. Yet when I plug the LaCie into the old computer, it shows up just fine.

I am wondering if this is an encryption thing? Do I need to erase/restore the LaCie on the old computer? I am a little reluctant to do this since there are some folders on the LaCie that are too big to store on my old computer. But both computers are under my AppleID and so far have been syncing folders and stuff just fine. When I did the data migration it seemed to go well.

Other possibly relevant info: my husband has a user on the new computer, it's version 14.2.1, Apple M2 chip. The old computer can't be updated anymore and is version 12.7.2.

Tl;dr: do I need to erase and decrypt the LaCie??

Any help would be appreciated.