Elasticsearch docs state this, have you done this to help diagnose the issue:
By default the Elasticsearch service doesn’t log information in the systemd journal. To enable journalctl logging, the --quiet option must be removed from the ExecStart command line in the elasticsearch.service file.
Another thought, are you always attempting to start elasticsearch with systemctl? What happens if you try to start elasticsearch by method below, while using needed arguments? I suggest this to pinpoint if error is related to your systemctl service configuration or the underlying file/folders that systemctl is interacting with.
./bin/elasticsearch