I'm using Plymouth to have a splash screen on my Raspberry Pi 3 with Raspbian (Stretch) and up to the middle of sequence, the screen background becomes black and just updates are shown. The boot sequence doesn't fail, just becomes in part black.
For example in 'script' Plymouth theme, at start blue background with the Debian logo in the middle of screen, and at the middle of boot only Debian logo with blue background the rest of screen becoming black.
I've tested with other themes fade-in, glow, joy, solar, spacefun, etc. All have the same trouble.