Some good info at:
https://github.com/systemd/systemd/issues/5497
So you likely have a result with "running" when doing:
systemctl status rc-local
And they suggest:
The only way to start a daemon in rc.local is by mean of "at -f <commandfile_that_includes_daemon> now", as atd runs in a separate cgroup thus rc.local gets no running PIDs in their group
Aieee! The only reason I'm starting things in rc.local is because systemd can't ever start them properly because it has no idea when the network is actually up. I guess I'll have to move all my rc.local content to a different script and start that script with the at -f now gimmick.
Thanks for the pointer!