How to map the size from dimensions to sizes[] for prebid.js

[580]

I am trying to setup a demo page with the sample from prebid.org. Here's the code snippet I am using:

arcAds.registerAd({
    id: 'div-1',
    slotName: 'header-bid-tag-0',
    adType: 'leaderboard',
    display: 'all',
    dimensions: '[[970, 250], [970, 90], [728, 90]]',
    sizemap: {
        breakpoints: '[ [1280, 0] ]',
        // refresh: 'leaderboard'
    },
    bidding: {
        prebid: {
            enabled: true,
            bids: [{
                bidder: 'appnexus',
                labels: ['desktop'],
                params: {
                    placementId: '13144370'
                }
            }]
        }
    }
})

Expected Behavior

Receive the bid from the auction request.

Actual Behavior

The auction failed with a {"error":"parse"} message.

Steps to Reproduce the Behavior

Looking into the bid request, you'll see the sizes[] from the payload is empty:

{
    "tags": [{
        "sizes": [],
        "ad_types": ["banner"],
        "uuid": "275015f90ea6f6",
        "id": 13144370,
        "allow_smaller_sizes": false,
        "use_pmt_rule": false,
        "prebid": true,
        "disable_psa": true
    }],
    "sdk": {
        "source": "pbjs",
        "version": "1.15.0"
    }
}

Additional Comments

Is there anything I've missed from the code? Or set the sizemap incorrectly?
Thank you so much for sharing the project. Any help would be appreciated.