SOLVED!
Hello! After I installed two PMG nodes for testing purposes the tracking center suddenly stopped working after a certain point, the GUI outputs: No data in database.
pmgversion -v
proxmox-mailgateway: 9.0.0 (API: 9.0.6/0a1e7f1cf8f3, running kernel: 6.17.9-1-pve)
pmg-api: 9.0.6
pmg-gui...