spfx – How to extract the Theme from a site in PnP provisioning for SP Online?

I am looking to extract a template with its theme from a site in SP Online. I have the code

Get-PnPProvisioningTemplate -Configuration "template.json" -Out "template.xml" -Force

and for the template.json

{
    "$schema": "https://aka.ms/sppnp-extract-configuration-schema",
    "persistAssetFiles": false,
    "handlers": [
        "Lists",
        "WebSettings",
        "Pages",
        "Theme"
    ],
    "lists": {
        "lists": [
            {
                "title": "Banner",
                "includeItems": true
            }
        ]
    },
    "navigation": {
        "removeExistingNodes": true
    },
    "siteFooter": {
        "removeExistingNodes": true
    },
    "pages": {
        "includeAllClientSidePages": true
    }
}

But when I save the file, there is no <pnp:Theme> element. However before I extracted it, I set a site theme on the site. Anyone know what’s wrong?

Thanks