Says reward expire and can’t be redeem in duo. My last 4 reward gone by saying this.my inviting friends got reward but i didn’t. I get reward in beginning but i was not get last 4 reward.
If you are having issues with rewards, I would read this here – https://googleduohelp.com/question/i-am-having-issues-claiming-and-earning-rewards-with-google-duo/
If you still have issues, theres a link there to submit your feedback for Rewards!
Hope this helps!