zfs tries to auto import pools at boot, if your pool is on a encrypted partition then it will fail to import, we need to be able to import after the encrypted partition is unlocked. A couple of things mentioned in chatting. https://github.com/zfsonlinux/zfs/commit/74497b7ab6af69434453e03c755d3f6e6e655aee spa_import_rootpool() (from Solaris zfs) Reproducible: Always
A workaround is in genkernel 3.4.40.