While attempting to build updated vagrant boxes with Packer (and then testing manually via the Parallels GUI), I found Debian 10.1/amd64 would consistently freeze on a black screen right after the boot command was run. The i386 installer worked OK, and amd64 worked fine on vmware/virtualbox.
Anyway adding vga=normal fb=false to the boot command resolved the issue.
Anyway adding vga=normal fb=false to the boot command resolved the issue.