Pre-filled variable value not passed to downstream multi project pipeline

Hello,
I’m making a multi project pipeline, but I’m having trouble with pre-filled variables.

My multi project pipeline can be reduced to:

variables:
  CI_DEBUG_TRACE: "true"
  TEST_VAR: "pouet"
  TAG_COMMITS:
    value: "false"
    description: "desc"

stages:
  - testage

var_print:
  stage: testage
  script:
    - echo "b"
    - echo $TAG_COMMITS

option_test:
  stage: testage
  trigger: 
    project: group/a_test1
    strategy: depend

and my triggered to:

variables:
  CI_DEBUG_TRACE: "true"

stages:
  - build

build_windows:
  stage: build
  script:
    - echo "a"
    - echo $TAG_COMMITS

My problem is that, when I start the multi project pipeline, set my variable manually to true, my downstream pipeline does not have the correct value:

My main pipeline resust:

$ echo "b"
b
$ echo $TAG_COMMITS
true

my triggered pipeline:

$ echo "a"
a
$ echo $TAG_COMMITS
false

Am i doing something wrong to actually inherit my variable?

Thanks