If you really installed v1.2.1 of the module, like the docs links you posted shows, please updated the module - v1.7.1 ist the most recent version - and check if that solves your problem.
Also “systemctl restart icinga-vspheredb.service” gives me this error:
Job for icinga-vspheredb.service failed because the control process exited with error code.
See “systemctl status icinga-vspheredb.service” and “journalctl -xeu icinga-vspheredb.service” for details.
*systemctl status icinga-vspheredb.service : service is enabled
*journalctl -xeu icinga-vspheredb.service : the only error here is:
░░ The unit icinga-vspheredb.service has entered the ‘failed’ state with result ‘exit-code’.
Feb 19 09:31:47 icinga-VMware-Virtual-Platform systemd[1]: Failed to start icinga-vspheredb.service - Icinga vSphereDB Daemon.