Armin, could you try booting with the option 'plymouth:debug=file:/var/log/plymouth-debug.log' added to the kernel command line, then attach any resulting /var/log/plymouth-debug.log file here?
Armin, could you try booting with the option 'plymouth: debug=file: /var/log/ plymouth- debug.log' added to the kernel command line, then attach any resulting /var/log/ plymouth- debug.log file here?