reproduction Flowgraph for https://github.com/gnuradio/gnuradio/issues/5359

defaults.ini

[bar]
value = 0

[baz]
value = 0

repro5359.grc

options:
  parameters:
    author: marcus
    catch_exceptions: 'True'
    category: '[GRC Hier Blocks]'
    cmake_opt: ''
    comment: ''
    copyright: ''
    description: ''
    gen_cmake: 'On'
    gen_linking: dynamic
    generate_options: qt_gui
    hier_block_src_path: '.:'
    id: repro5359
    max_nouts: '0'
    output_language: python
    placement: (0,0)
    qt_qss_theme: ''
    realtime_scheduling: ''
    run: 'True'
    run_command: '{python} -u {filename}'
    run_options: prompt
    sizing_mode: fixed
    thread_safe_setters: ''
    title: Var Config repro
    window_size: (1000,1000)
  states:
    bus_sink: false
    bus_source: false
    bus_structure: null
    coordinate: [32, 20.0]
    rotation: 0
    state: enabled

blocks:
- name: config0
  id: variable_config
  parameters:
    comment: ''
    config_file: defaults.ini
    option: value
    section: section_var
    type: real
    value: '0'
    writeback: mutable_var
  states:
    bus_sink: false
    bus_source: false
    bus_structure: null
    coordinate: [32, 116.0]
    rotation: 0
    state: enabled
- name: mutable_var
  id: variable_qtgui_chooser
  parameters:
    comment: ''
    gui_hint: ''
    label: choice
    label0: ''
    label1: ''
    label2: ''
    label3: ''
    label4: ''
    labels: '[]'
    num_opts: '3'
    option0: '0'
    option1: '1'
    option2: '2'
    option3: '3'
    option4: '4'
    options: '[0, 1, 2]'
    orient: Qt.QVBoxLayout
    type: real
    value: '0'
    widget: combo_box
  states:
    bus_sink: false
    bus_source: false
    bus_structure: null
    coordinate: [208, 116.0]
    rotation: 0
    state: enabled
- name: section_var
  id: variable_qtgui_chooser
  parameters:
    comment: ''
    gui_hint: ''
    label: section
    label0: ''
    label1: ''
    label2: ''
    label3: ''
    label4: ''
    labels: '[]'
    num_opts: '3'
    option0: foo
    option1: bar
    option2: baz
    option3: '3'
    option4: '4'
    options: '[0, 1, 2]'
    orient: Qt.QVBoxLayout
    type: string
    value: foo
    widget: combo_box
  states:
    bus_sink: false
    bus_source: false
    bus_structure: null
    coordinate: [336, 116.0]
    rotation: 0
    state: enabled
connections: []

metadata:
  file_format: 1
  grc_version: v3.11.0.0git-649-gd7cdf222