Just to clean this up, the issue was a bug (multiple actually). A patch applied this morning to dracut under SLES 15 SP1 (also available for SLES 12 SP4/5) fixes it all;

Reference https://www.suse.com/support/update/...ru-20200662-1/

SUSE Linux Enterprise Module for Basesystem 15-SP1 (aarch64 ppc64le s390x x86_64):

dracut-044.2-18.51.1
dracut-debuginfo-044.2-18.51.1
dracut-debugsource-044.2-18.51.1
dracut-fips-044.2-18.51.1
dracut-ima-044.2-18.51.1