Installer Black Screen RHEL 8.0.0 MacBook Pro 16GB 2xHD

Trying to install in a multi-boot environment using a USB device and rhel-8.0-x86_64-dvd.iso. The installer boots the kernel and comes up with the first screen, but stops at a black screen with a character cursor flashing in the upper left of screen, about 10-15 sec after arrowing down to "Install RHEL 8.0.0" and pressing Enter. Activity light on the USB drive (ISOStick) stops flashing then. Ctrl/Alt/F1-2-3... has no effect. Obviously can't ssh in as no installation has been done and the sshd not started, but just to be complete, I tried both ping and ssh to the IP that our DHCP will give the machine, nothing doing on either.

Machine has 2 HDs, the first has among others a Ubuntu partition and a Windows Recovery partition that I will free up when/if I get the installer to get that far. First HD is fdisk partitioned and the second is GUID. I doubt the kernel has a problem with this as Ubuntu and 2 other OSes boot up OK on the machine (one from each disk, using rEFInd).

I have compared (twice, using cmp and again w/ md5) the file I downloaded and used to install successfully under VirtualBox with the CD-ROM image presented by the ISOStick, and they are identical.

Anyone who knows the installer innards (as opposed to random guessing :-)) please help me get over this hurdle? TIA!