Linux journalctl not synced with systemctl status / Journalctl not updating
Solution 1:
Try adding these lines to your service file under the [Service] tag
StandardOutput=journal
StandardError=journal
Then do a systemctl daemon-reload, then do a systemctl restart your_service.service
I edit the answer for others to see it easily. Problem was lack of space on /var filesystem so journalctl was not able to save logs to disk and read afterwards, that is why there was a difference between systemctl status and journalctl -fu .