Is anybody having problems with incoming calls today?
Works fine here, make sure your notifications are set to on/allowed in settings of hangouts app, and volume is on if you want it to ring, as well as your app is up to date, and if needed to have a verification code sent to re-verify your number( it seems with the new update they took away that cranky ennoying step to keep your numbers active).
Lastly you can try clear cache ,the data on the app.
And last but not least make sure people are really calling you.
You can play around with your phone yourself and use this free site to call yourself and see when you get it to work, good luck.
https://www.callmylostphone.com/