Then it is usb detection issue on host. Try to enable these logs on your host and start the flash process. Share the dmesg on your host.
echo 8 > /proc/sys/kernel/printk
echo ‘module usbcore +p’ > /sys/kernel/debug/dynamic_debug/control
echo ‘module xhci_hcd +p’ > /sys/kernel/debug/dynamic_debug/control
You could also try other usb cable/ports (host side) or other host machines.