To reproduce the problem at bionic I had to uninstall the cryptsetup-package and use DeviceTimeout 1 at /etc/plymouth/plymouthd.cfg. After installing plymouth:i386 0.9.3-1ubuntu7.18.04.2, the problem disappeared. Problem solved.
To reproduce the problem at bionic I had to uninstall the cryptsetup-package and use DeviceTimeout 1 at /etc/plymouth/ plymouthd. cfg. 18.04.2, the problem disappeared.
After installing plymouth:i386 0.9.3-1ubuntu7.
Problem solved.