Timer duration doesn't change

[Marquo1]

Hi! In the past, using the card I could permanently change the duration of a timer. Now once the timer runs out, it resets to previous duration. Can something be done to restore that functionality?

Card config:

      type: custom:numberbox-card
      entity: timer.e_blanket_left
      icon: false
      name: false
      service: timer.start
      param: duration
      state: duration
      min: 0
      max: 1800
      step: 30
      unit: time