I'm trying to create a own product based on SLE-12-Server (yast2-product-creator-3.1.5-1.204.noarch)
It failed with the following error:

Could not ad GPG key XXXXXXXX to initrd

So far I see this is because now xz insted gzip for initrd compression is used.
If is modify the ProductCreator.rn fil ethis way I get a bootable iso.

But here the boot failes with the following error.

List of all partitions:
No filesystem could mount root, tried:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Does anyone have an idea?
Maybe the kernel itsself or its module with the inird have to be signed as well with the own key????