Statistics sensor has count 0 and state unknown

i have a sensor measuring the current ampere my laundry machine is consuming. I want to create a statistics sensor based on that sensor. So here is my config:

- platform: statistics
 entity_id: sensor.badezimmer_waschmaschine_energy_current
   minutes: 60
 name: "Badezimmer Waschmaschine Durchschnitt"
 sampling_size: 200

As a result i get the sensor, but it has no meaningful values:
State: Unknown

sampling_size: 200
count: 0
mean: unknown
median: unknown
standard_deviation: unknown
variance: unknown
total: unknown
min_value: unknown
max_value: unknown
min_age: 2021-02-14T09:12:55.910984+00:00
max_age: 2021-02-14T09:12:55.910984+00:00
change: unknown
average_change: unknown
change_rate: unknown
friendly_name: Badezimmer Waschmaschine Durchschnitt
icon: mdi:calculator

However, the basic current sensor is happily reporting that the machine is currently not in use and therefore consuming 0 Amps. What bugs me is that even the count value of the statistics sensor is showing a 0 value - why?