What is your default shell: env | grep SHELL ? I think the init system is using /bin/sh, which might not like your multiple command not using the multiline separator. Try /bin/sh /etc/init.d/rclone start from command line.
START=6 could be too aggressive: the network is not up yet. Does rclone come up without a network? Try START=99.
Add exec >>/root/rclone.log 2>&1 before the first function to get all the output into a file. This way you will not be flying blind.