In 1.6.6-2 there is only systemd service and not init.d now, can you test if 1.6.6-2 is ok for you?
about the build its self I saw that fails strange in some cases (trying to build in ubuntu 20.04 for example), init.d files was not generated in build and fails on rm them in debian/rules (workaround with rm -f) and dh_missing fails for strange error of service files "present in build but not installed" (that should not happen), with latest version need compat 13 and on debian/ubuntu system with debhelper >=13 build correctly from a fast tests, I'll probably prepare buster-backports build too, if still fail for you can tell me in what case please?
