Proxmox VE sends the data over UDP, so the influxdb server has to be configured for this.
Proxmox is using UDP (Influx V1 compatible)
Install Telegraf Socket listener plugin
https://hub.docker.com/_/telegraf
echo "my_measurement,my_tag_key=my_tag_value value=1" | nc -u -4 -w 1 docker-host 3522
Most dashboards are written to support Influx v1 (SQL like queries).