ansible json_query to count healthy targets in a AWS target group

Question

Cannot figure this json_query out, I'm using Ansible and json_query to (try to) count all healthy targets in a targets group.

So I have this to get the info

- name: Query target group
  elb_target_group_info:
    names: my-target-group-name
    collect_targets_health: true
  register: target_group_info

Then I try to simply print the number of healthy targets, like this:

- name: Debug
  debug:
    msg: "{{ target_group_info | json_query('target_groups[*].targets_health_description[*].target_health[?state==''healthy'']') | length }}"

and I just get an empty list:

    "msg": [
        0
    ]

I've tried numerous different queries and now just fumbling around, not a clue. I'm interested in the json_query to get what I need, and also any tips how to quickly iterate testing json_query queries with mock input.

Many thanks!