I followed a rather lengthy process of rooting my Pixel 2 using Android 9 and then installed the PortSwigger certificate file into my Android's /system/etc/security/cacerts, finally I changed permissions. That all worked, in fact, the cert is valid and is now enabled in my Android Trusted Certs settings. I then set up my proxy settings on my WiFi connection to route thru my machine running Burp Suite. This worked as well, as I am able to intercept HTTP traffic and SOME HTTPS traffic. However, I am not able to intercept most HTTPS traffic it seems... And if I go to https://google.com for example, I get the insecure page warning.
Does anyone know what could be causing this and a way to get better functionality out of Burp proxy with Android? Thanks.
Instructions followed:
https://support.portswigger.net/customer/portal/articles/1841102-Mobile%20Set-up_Android%20Device%20-%20Installing%20CA%20Certificate.html
https://support.portswigger.net/customer/portal/articles/1841101-configuring-an-android-device-to-work-with-burp
https://ivrodriguez.com/installing-self-signed-certificates-on-android/