Pi 3b+ SSD boot (it won’t)

Ok, so I used pi imager to write ha image to kodak ssd, plugged it into the pi and nothing happens. Waited over half an hour.
I’ve read pi docs and it says 3b+ boots from usb ‘out of the box’
I’m kinda guessing that only applies to a raspbian image.
Had a good Google but I couldn’t find any info that I trust.
Can any of you well informed people give me any pointers?
Thanks in advance.

You did flash the correct image (Rbpi 3 32 bit or Rbpi 3 64bit) ?

tl;dr

  • Boots with a USB2 flash drive.
  • Fails to boot with a USB3 SSD.

Use USB2 interface with RPi 3 B.

Yes I did. I’m going to erase the drive and try again