I just updated to Debian "4.19.0-0.bpo.1-amd64 #1 SMP Debian 4.19.12-1~bpo9+1 (2018-12-30) x86_64 GNU/Linux"
Even without the "rootdelay" boot option, the boot process proceeds now as it should again.
I just updated to Debian "4.19.0- 0.bpo.1- amd64 #1 SMP Debian 4.19.12-1~bpo9+1 (2018-12-30) x86_64 GNU/Linux"
Even without the "rootdelay" boot option, the boot process proceeds now as it should again.