Looks like RPI-Imager is having problems with bookworm since it seems to be using one set of partitions ids for any flashes.
Did the flash using BalenaEtcher on my pc and when I plugged the drive into this machine it automounted and was listed in Nemo as expected.
Guess I will have to find a better flash tool to replace RPI_Imager.
Thank you for your help. Would never have found the root problem without your help.