OWC Envoy Ultra 4TB SSD Tb5 Not mounting

I bought a very fast OWC Envoy Ultra (thunderbolt5 backwards) 4 Tb and

1. I installed it - using the script that OWC has in the file (it formats the disk), I did not use Disk Utility.
2. Then I copied the files from other drives to the Envoy.
3. I checked they were there. They were.

So far so good.

But now the Envoy . . . does not mount. The light does not go on.

I restarted the Studio, no result.

HW: Studio M1Max, four TB slots on the back. Sequoia 15.1+

What can be a problem?