Works for me in debian-10 TemplateVM.
dpkg -l | grep security-misc
ii security-misc 3:8.2-1 all enhances misc security settings
ii tor 0.4.1.5-1~d10.buster+1 amd64 anonymizing overlay network for TCP
I am not familiar with vanguards.
The mix with it may be the cause. However, even that works for me.
sudo systemctl status vanguards
● vanguards.service - Additional protections for Tor onion services
Loaded: loaded (/lib/systemd/system/vanguards.service; disabled; vendor preset: enabled)
Active: active (running) since Mon 2019-09-09 08:28:08 EDT; 20s ago
Docs: man:vanguards(1)
Main PID: 4485 (vanguards)
Tasks: 3 (limit: 4667)
Memory: 84.7M
CGroup: /system.slice/vanguards.service
└─4485 /usr/bin/pypy /usr/bin/vanguards
Sep 09 08:28:08 atest-debian-10-based systemd[1]: vanguards.service: Main process exited, code=killed, status=15/TERM
Sep 09 08:28:08 atest-debian-10-based systemd[1]: vanguards.service: Succeeded.
Sep 09 08:28:08 atest-debian-10-based systemd[1]: Stopped Additional protections for Tor onion services.
Sep 09 08:28:08 atest-debian-10-based systemd[1]: Started Additional protections for Tor onion services.
Sep 09 08:28:08 atest-debian-10-based vanguards[4485]: NOTICE[Mon Sep 09 08:28:08 2019]: Creating new vanguard state file at: /var/lib/tor/vanguards.state
Sep 09 08:28:08 atest-debian-10-based vanguards[4485]: NOTICE[Mon Sep 09 08:28:08 2019]: Vanguards 0.3.0 connected to Tor 0.4.1.5 using stem 1.7.1