Template sensor "unknown" problem

i am trying to understand the paragraph “Considerations” -> “Startup” in https://www.home-assistant.io/integrations/template and it’s unclear to me.
i am using the following sensor:

  - platform: template
        value_template: '{{states("sensor.lsx_latitude")}},{{states("sensor.lsx_longitude")}}'

this sensor is getting a state “unknown” on start up even though both sensor.lsx_latitude and sensor.lsx_longitude do have values.

how do i fix this?

value_template: '{{ states("sensor.lsx_latitude"),states("sensor.lsx_longitude") }}'

the problem with what you suggested is that the resulted state is the coordinates wrapped with brackets () for some reason, which isn’t good.
also - what do you make of this from the manual:
replace {{ states.cover.source.state == 'open' }} with {{ is_state('switch.source', 'on') }}
i don’t see any connection between the two - is this a mistake?

It seems to be…