It was years ago since I last used flash-sdcard.sh for my LPC boards, but I remember that it had mixed success. One time it worked, and the next day it failed for whatever reasons.
I finally upgraded all to the Katapult bootloader and was done with it. So if you feel like doing so, find an instruction here: CanBoot: Flash BTT SKR 1.3 / 1.4 / 1.4 Turbo