Try to recreate the drive and copy the output from the terminal for review.
Ok thanks, I will do this. FYI - I created the bootable flash drive using the Terminal commands you posted above in #45. No errors were reported in Terminal. The error showed up as a window in macOS when attempting to boot from the flash drive after holding down Option key and selecting the flash drive as boot drive. But will recreate it again and paste the Terminal output here. Thanks again.