Figured it out. It was not Adguard. It was the VPN firefox addon Windscribe which has an adblocker in it which was causing it.
Turned off the adblock feature in it. Now the page loads normally. :)
This usually happens for me when you install/reinstall firefox with adguard running or create a new profile. Though the above article sometimes work for me.. the absolute solution that worked for me is to completely uninstall and reinstall adguard.
Had discussed this before here