@evin.polack Try a soft restart on your pixel by holding the power and volume down at the same time and release both when the screen shuts off. Also as I’m sure you know play/pause is controlled by single quick tap of the middle multifunction button. Like @elmo41683 said it also depends on the mucic player you are using. I have the same headphones and they control google music, Spotify, SoundCloud and Pandora perfectly. There is also an app called headset button controller that will give you extra functionality.
There’s also an app called Android headset tester to test the buttons and mic. This app was designed for testing wired apple headphones functionality on Android devices but if memory serves it will also work with Bluetooth headphones. I gave my set of curves to my brother after receiving the zolo liberty+ otherwise I would have tested it for you. Let me know how it works out for you.