Nextcloud how to set maintenance_window_start correctly?

I have added the following additional parameter to nextcloud official app:

maintenance_window_start
with a value of 1,

but it does not seem to be working, since nextcloud is still complaining about the maintainence window not being set. Does anyone know what the correct keyword is to set this? Or where I can look up these things?
https://docs.nextcloud.com/server/28/admin_manual/configuration_server/background_jobs_configuration.html