Actually, my apologies, I am not (and I can't figure out how to edit my last comment, if it is possible) ...
I was in 18.04 Workstation with GUI disabled when I was adding consoleblank to GRUB_CMDLINE_LINUX_DEFAULT - that wasn't working at all in Server though, so I tried adding it to GRUB_CMDLINE_LINUX and I am AMAZED to see that the display is actually OFF for the first time in 3-4 weeks I've been fighting with all this. No issues here, please disregard my previous comment!
Actually, my apologies, I am not (and I can't figure out how to edit my last comment, if it is possible) ...
I was in 18.04 Workstation with GUI disabled when I was adding consoleblank to GRUB_CMDLINE_ LINUX_DEFAULT - that wasn't working at all in Server though, so I tried adding it to GRUB_CMDLINE_LINUX and I am AMAZED to see that the display is actually OFF for the first time in 3-4 weeks I've been fighting with all this. No issues here, please disregard my previous comment!