We have updated our documentation with the
odoo-server.conf line fix.
Now, regarding scheduled actions, we have been able to reproduce your issue. However, it seems to happen in the official Community images of Odoo as well, since jobs are not getting run (the number of executions does not increase, and the date for the next execution does not change).
Could you let us know if this only happens to you when configuring a sub-domain multi-database (and it works in a normal install)? If so, could you let us know how you are configuring your Scheduled Action?