Comment 20 for bug 1850130

Good to know, thanks. Maybe something in the reboot process is exporting these extra pools, causing them to be removed from the cache.

Have you guys also tried editing /etc/default/zfs and listing your extra pool(s) there? Specifically:

# List of pools that SHOULD be imported at boot by the initramfs
# instead of trying to import all available pools. If this is set
# then ZFS_POOL_EXCEPTIONS is ignored.
# Only applicable for Debian GNU/Linux {dkms,initramfs}.
# This is a semi-colon separated list.
#ZFS_POOL_IMPORT="pool1;pool2"

There is also ZPOOL_IMPORT_ALL_VISIBLE='no' with a big disclaimer on top of it.

Not saying that the current behaviour isn't a bug: just investigating options.

Might need an initramfs update after changing anything in that file, tough.