nightmare.js e2e testing paypal payment

I am end-to-end testing placing and order and paying it on a custom webshop, and I have several payment providers all running fine, with nightmare.js on linux xubuntu 16.04 but similar results were achieved on a OSX box:

"dependencies": {
    "electron": "^2.0.5",
    "merge": "^1.2.0",
    "nightmare": "github:segmentio/nightmare",
    "vo": "^4.0.2"
  }

Once launched, clicking the paypal button does nothing, and even clicking on the paypal button in electron manually does not work, throwing no errors.

Please find below the relevant electron initialization params, which I believe to have tested in all possible combinations (current config is shown, but several dozens more were tested).

var nightmare = Nightmare({
[...omissis],
webPreferences: {        
        partition: 'persist:random-'+parseInt(Math.random()*1000000),
        nodeIntegration: false,
        nodeIntegrationInWorker: false,
        webSecurity: false,
        allowRunningInsecureContent: true,
        nativeWindowOpen: false,
      }

Can someone please shed some light on how to proceed with testing? Or even better, how to address such issue?

Please note: all other payment providers (direct credit card, and other banks) work, including some with nasty redirects such as Mastercard 3d.