1) deployed the machine using flat layout on /dev/sda only
2) added the partition to /dev/nvme0n1 - which triggered the udev rule for bcache to consume the device.
3) at this point in time it was not possible to wipefs the partition as it was busy
4) stopped the bcache cache device using echo 1 > /sys/fs/bcache/bab46690-0a04-418b-8c1b-41df57821259/stop
5) wipefs -a /dev/nvme0n1p1
Released, reconfigured and re-deployed the machine using bcache layout with multi bcache devices and the machine now fully deploys with the required configuration.
OK so that appears to have done the trick; we:
1) deployed the machine using flat layout on /dev/sda only bcache/ bab46690- 0a04-418b- 8c1b-41df578212 59/stop
2) added the partition to /dev/nvme0n1 - which triggered the udev rule for bcache to consume the device.
3) at this point in time it was not possible to wipefs the partition as it was busy
4) stopped the bcache cache device using echo 1 > /sys/fs/
5) wipefs -a /dev/nvme0n1p1
Released, reconfigured and re-deployed the machine using bcache layout with multi bcache devices and the machine now fully deploys with the required configuration.