Disk Utility won't format new Extreme Portable SSD

I just bought a 4 TB SanDisk Extreme Portable SSD. I’ve tried to erase/format it with Disk Utility on two different computers: a new 14" MacBook Pro, and a 2017 iMac Pro. I clicked on the external volume, selected erase, then AFPS for file system, then clicked the “Erase” button.

The drive disappears from the desktop, but Disk Utility seems to get stuck on the “Unmounting Disk” step. It says “Erasing ‘Extreme SSD’ (disk4s1) and creating ‘Photos’” and then under that it says “Unmounting Disk”, but after 10 minutes nothing has happened.

What’s going on?

Hi @switters,

Please refer to the below link to check formating on a Mac Device: