Reference/Test images are not captured in jenkins and debug logs are not printed

I am executing the tests in Jenkins and i see that the reference/test images are not captured. Also the debug logs were not printed. The same code works fine in my windows local and in my vagrant unix box. I have verified that the URL is accessible from the jenkins machine and valid chrome browser is already installed. Wondering why the debug logs are not printed and also i dont see this message "9237 INFO > BackstopTools have been installed." in the console. Any help is appreciated.

.json
--------
{
"id": "SG",
"viewports": [
{
"label": "320x568",
"width": 320,
"height": 568
},
{
"label": "768x1024",
"width": 768,
"height": 1024
},
{
"name": "1024x768",
"width": 1024,
"height": 768
},
{
"name": "1280x1024",
"width": 1280,
"height": 1024
}
],
"paths": {
"bitmaps_reference": "ci/bitmaps_reference",
"bitmaps_test": "ci/bitmaps_test",
"engine_scripts": "ci/engine_scripts",
"html_report": "ci/html_report",
"ci_report": "ci/ci_report"
},
"report": [
"browser",
"local"
],
"engine": "chrome",
"engineFlags": [],
"asyncCaptureLimit": 4,
"asyncCompareLimit": 100,
"debug": true,
"debugWindow": false,
"engineOptions": {
"waitTimeout": 30000
},
"scenarios": [
{
"label": "Home page",
"url": "https://www.aviva.com.sg/en/",
"delay": 10000,
"readySelector": "html.components-loaded",
"selectors": ".hero",
"selectorExpansion": true,
"misMatchThreshold": 0,
"requireSameDimensions": true
}
]
}

Log:
-----------
17:14:56 [INFO] BackstopJS v3.8.5
17:14:56 [INFO] Loading config: /var/lib/Test/workspace/ci/backstop.json
17:14:56 [INFO]
17:14:56 [INFO] COMMAND | Executing core for "reference"
17:14:56 [INFO] clean | ci/bitmaps_reference was cleaned.
17:14:56 [INFO] createBitmaps | Selected 1 of 1 scenarios.
17:14:56 [INFO] searching for 4 available ports.
17:14:56 [INFO] These ports will be used: [9247,9248,9249,9250]
17:14:56 [INFO] Starting Chromy: {"chromeFlags":["--disable-gpu","--force-device-scale-factor=1","--disable-infobars=true","--window-size=320,568"],"port":9247,"waitTimeout":30000,"visible":false}
17:14:56 [INFO] CREATING NEW REFERENCE FILES
17:14:56 [INFO] Starting Chromy: {"chromeFlags":["--disable-gpu","--force-device-scale-factor=1","--disable-infobars=true","--window-size=768,1024"],"port":9248,"waitTimeout":30000,"visible":false}
17:14:56 [INFO] CREATING NEW REFERENCE FILES
17:14:56 [INFO] Starting Chromy: {"chromeFlags":["--disable-gpu","--force-device-scale-factor=1","--disable-infobars=true","--window-size=1024,768"],"port":9249,"waitTimeout":30000,"visible":false}
17:14:56 [INFO] CREATING NEW REFERENCE FILES
17:14:56 [INFO] Starting Chromy: {"chromeFlags":["--disable-gpu","--force-device-scale-factor=1","--disable-infobars=true","--window-size=1280,1024"],"port":9250,"waitTimeout":30000,"visible":false}
17:14:56 [INFO] CREATING NEW REFERENCE FILES
17:14:58 [INFO] 9248 Chrome v70 detected.
17:14:58 [INFO] 9249 Chrome v70 detected.
17:14:58 [INFO] 9247 Chrome v70 detected.
17:14:58 [INFO] 9250 Chrome v70 detected.
17:15:28 [INFO]
17:15:28 [INFO] Run `$ backstop test` to generate diff report.
17:15:28 [INFO]
17:15:28 [INFO] COMMAND | Command "reference" successfully executed in [32.054s]
17:15:29 [INFO] ------------------------------------------------------------------------
17:15:29 [INFO] BUILD SUCCESS