Append To List just overwrites the current List

I have this snippet in my Keyword to store all ids in the test_id_list, but it doesn't seem to work as the latest test_id just overwrites the previous test_id, it does not add to the list.

${test_id}    Get Value From JSON    ${response}    $.id${test_id}    Get From List    ${test_id}    0${test_id_list}    Create ListAppend to List    ${test_id_list}    ${test_id}

I have tried:

Removing the 3rd line and declare it like @{test_id_list}= Create ListAND not removing the 3rd line but just changed it to "@{test_id_list}"