installboot(1M) lists wrong binary for 64-bit EFI boot
manpage - manual pages
Currently, installboot(1M) says:
The x86 UEFI systems load and start boot loader program from /EFI/Boot directory of the EFI System Partition (ESP). The boot loader program in ESP is named bootx86.efi for AMD64 system and bootia32.efi for i386 system. Note, only a 64-bit kernel is supported, even on i386 systems. The bootia32.efi boot program is only provided to support systems with 32-bit UEFI firmware, but which can support 64-bit mode. The bootx86.efi is copied from /boot/loader64.efi and bootia32.efi is copied from /boot/loader32.efi.
The 64-bit loader is actually bootx64.efi