RHEL 8 install hung at "Installing boot loader" on HP Z2

On a new HP Z2 G4 workstation, I'm trying to install RHEL 8 from a usb stick with the full dvd iso on it. The installation gui proceeds until at the bottom it says:

Installing boot loader

at which point it is hung.

I tried completely erasing the partitions using gparted and trying again, but the same thing happens. Gparted had no complaints about writing a new partition table, either msdos or gpt.

Previous steps to get the usb stick to even boot included disabling Secure Boot in the BIOS and leaving 'legacy' booting disabled.

Suggestions?