I found something interesting while following your advice.
I uninstalled AdblockPlus for Android, but I didn't change the proxy settings in Settings -> Wi-Fi -> Wi-Fi networks: [name of network] -> Modify network config -> Advanced options: Proxy. So technically I should be getting connection timed out or reset for all internet, but instead I see that some apps error out (android's built in "internet", Google's YouTube, Google Plus, Imgur, Facebook, Google Chrome) but other apps are still making successful internet accesses (WeatherUnderground, Netflix, Google Maps, Lightning browser, Google Drive, ServStream).
It seems some Android apps are ignoring the network configuration for using an http proxy. Maybe this is why AdblockPlus isn't working?