Tumbleweed: Pre-Existing Software Raid not recognized during installtion but fine after booting


I am trying to install Tumbleweed alongside Leap 15.1 on a Linux Software Raid. During installation Leap 15.1 and 15.2 recognize the software raid (live system) tumbleweed does recognize the software raid after starting but not during the installation, so it is impossible to install tumbleweed on a pre-existing linux software raid.

The funny thing is that on a console (CONTROL+ALT+F2)
mdadm --auto-detect
produces a correct /proc/mdstat file, showing totally correct entries.
mdadm --detail /dev/md127
also shows correct entries that show the RAID layout in a perfectly correct manner

extend libstoragemgmt
also returns no error, while
lsmcli --help returns an error (a funny one):
(Traceback most recent call last)

file ‘/usr/bin/lsmicli’ line 18 in <module>
then it refers to phyton3 calls and in the end it says
ModuleNotFoundError: No module name lsm._clib

which looks to me as if it was a configuration error.
But I am not sure what to check next.
I am also not sure whether I just got a version of tumbleweed that had an error that has gone away already.

If I install tumbleweed on non raid drive the partition tool of YAST2 recognizes the software raid and displays all information correctly.

Any help is appreciated.
kind regards