I had the same problem. Superb sound and ease of use, but... Siri didn't work, pausing didn't work. I tried a thousand times, almost knocking it out of my ear. ;-)
Until I tried the left airpod. Never thought of it, since I am right handed. The left one worked. Wow.... Then I found out a little secret, maybe it works for you too:
Open the case and select (on your iPhone) your airpods in the Bluetooth menu by tapping on the 'i'. Scroll to microphone and select allways right. Does it work now, Siri and pausing (of course you have to choose between the two)? It did for me. Out of the blue. Then try allways left. For me it even worked (on both ears) when I changed back to Automatic. Amazing.
Hope it works for you too!
Now I only have one problem left to solve: the hiss when I play back voice recordings using the airpods... :-(