"[object Object]": null error when trying to use template in data: data: of Live Activity

Configuration
,
1

I am trying to create a Live Activity that will display my 3D print’s progress. However, whenever I try to use a template to get the current progress, it turns itself into "[object Object]": null. The YAML I am trying to use is:

- action: notify.mobile_app_[my_device_identifier]
            metadata: {}
            data:
              data:
                tag: p1s
                live_update: true
                progress: {{ states("sensor.p1s_01p00c4c2300887_print_progress") }}
                progress_max: 100
                notification_icon: mdi:printer-3d-nozzle
                notification_icon_color: 5f68bd
              message: >-
                Current stage: {{
                states("sensor.p1s_01p00c4c2300887_current_stage")}}
              title: P1S Print Progress

However, the

progress: {{ states("sensor.p1s_01p00c4c2300887_print_progress")}}

turns itself into

progress:
    "[object Object]": null

Can anybody shed some light on why this isn’t working?

Thanks in advance!

2 
progress: "{{ states('sensor.p1s_01p00c4c2300887_print_progress')}}"

Single line templates require quotes.

3

Just be careful when adding surrounding quotes, they need to be the opposite of the quotes you’re using in the template itself… ie. single or double quotes.