Bidders not coming in/showing until I open devtools, Appnexus adapter returns parse error

[svyoung]

Type of issue

Bug, Question

Description

Very new to Prebid/Header bidding. I've done the basic set up with Prebid.js and am facing 2 issues I cannot find the solution for.

1. Headerbid Expert extension shows that there are 0 bidders on page load, with DFP showing as a listed bidder:

But when I open Chrome's devtool/console, the bidders start to show. However, even though the bidders took, it shows that the bids don't count because they loaded much later.

2. This probably means I've configured it incorrectly. I've gotten as far as MESSAGE: Emitting event for: bidRequested and get an error with AppNexus's adapter -> ERROR: in response for appnexus adapter: parse

The code setup (with params redacted):

bids: [
            {
              bidder: 'appnexus',
              labels: ['desktop', 'tablet', 'phone'],
              params: {
                placementId: ''
              }
            },
            {
              bidder: 'openx',
              labels: ['desktop', 'tablet', 'phone'],
              params: {
                delDomain: '',
                unit: ''
              }
            },
            {
              bidder: 'rubicon',
              params: {
                accountId: '',
                siteId: '',
                zoneId: '',
                sizes: [55,2]
              }
            }
          ]

Any clue what I am doing wrong? Here's what the PBJS debug messages say:

Platform details

Prebid v2.34.0 Chrome v75.0.3770.142 NPM v10.16.3

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