HA stopped graphing values in "status" page

Configuration Frontend
1

Hello,
yesterday evening i put online my custom-made air sensor (pm 1.0, 2.5 and 10). I integrated it via mqtt and all seems ok. This morning i just wanted to check everything was ok, but i found this graph:

image
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did the sensor stop? did something broke?
well it seems not the sensor. If i “show more” (but you can see also from the first line) the sensor is indeed working, and the values are saved by HA:
image
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so why am i not seeing values in the status page of the sensor?
I tried restarting HA with no results.
All the (six) sensors have the same problem.
Older entities / different sensors shows values correctly
Any idea?

sensors are configured like this:

    - name: "pm10_ae"
      unique_id: "PMSA003_home_pm10ae_sensor"
      device_class: "pm10"
      state_class: "measurement"
      state_topic: "devices/data/sprinkler/air"
      unit_of_measurement: "µg/m³"
      suggested_display_precision: 0
      value_template: "{{ value_json.pm10ae }}"

Thanks