Gray Blank and Mostly Blank/Gray images getting captured

It seems that this is similar to the issue that led to the introduction of the puppeteerOffscreenCaptureFix feature, however it's not fixing the captures for me. I've managed to reproduce the issue with the following config. When I run backstop reference and backstop test the result is nothing but gray boxes.

```json
{
"id": "backstop_default",
"viewports": [
{
"label": "phone",
"width": 320,
"height": 2000
},
{
"label": "tablet",
"width": 1024,
"height": 2000
}
],
"onBeforeScript": "puppet/onBefore.js",
"onReadyScript": "puppet/onReady.js",
"scenarios": [
{
"label": "Hotmail?",
"url": "https://outlook.live.com/owa/",
"referenceUrl": "",
"readyEvent": "",
"readySelector": "",
"delay": 0,
"hideSelectors": [],
"removeSelectors": [],
"hoverSelector": "",
"clickSelector": "",
"postInteractionWait": 0,
"selectors": [
".premium-appeal"
],
"selectorExpansion": true,
"expect": 0,
"misMatchThreshold" : 0.1,
"requireSameDimensions": true
}
],
"paths": {
"bitmaps_reference": "backstop_data/bitmaps_reference",
"bitmaps_test": "backstop_data/bitmaps_test",
"engine_scripts": "backstop_data/engine_scripts",
"html_report": "backstop_data/html_report",
"ci_report": "backstop_data/ci_report"
},
"report": ["browser"],
"engine": "puppeteer",
"puppeteerOffscreenCaptureFix": true,
"engineOptions": {
"args": ["--no-sandbox"]
},
"asyncCaptureLimit": 1,
"asyncCompareLimit": 1,
"debug": false,
"debugWindow": true
}
```