Help with troubleshooting - unable to add an entity tag to a modded entity using datapack

the bosses.json file is in the file path data/c/tags/entity_type/bosses.json filepath,
contents are:
{
    "replace": false,
    "values": [
        "aquamirae:captain_cornelia"
    ]
}
But it is not being reflected in game, how do i diagnose this further?