On Android,
- Long press on Google Duo > tap on info button (with an i symbol)

- From the screen that opens up, tap on Permissions
- You should see two sections Allow and Denied.

- As you can see, in my Android phone Google Duo is allowed to access contacts. So, the Allow option is selected.
On iPhone
- Launch Settings App
- Go to Privacy > select Contacts
- Now, you should see the apps that have access to the Contacts present on your iPhone.
- It must have Google Duo on it. Make sure the toggle beside it is enabled.
Note
When you install Google Duo and access it for the very first time, the app will by default ask you permission for accessing Contacts and other required things for it to work as it is designed. Only if you Allow it the necessary permissions, the same will show up in the Settings. This applies to both Android OS and iOS.
Have you saved the contact details like the phone number of the person you are trying to connect correctly on your device.? Otherwise, Google Duo will mark the number/potential contact as alien. So, check-in your Contacts list if you have saved the correct number. Otherwise, for video calling the concerned person is using a different number.
Clear the App Cache
Sometimes junk files such as the temporary files keep accumulating in the memory-making the memory unavailable for various tasks of an app. So, you end up facing issues such as app crash, slow down, a particular feature not working, etc. So, the fix is to clear the cache of the app which in this case is Google Duo. This method is only applicable to Android OS.
- Go to Setting > Apps & Notitifcations
- Under See All Apps > Scroll down to Google Duo. Tap on it to open it.

- Then tap on Storage & Cache > tap Clear Cache
- Reopen the app
Now, try to connect to your contact through video calling. It should work finely.
So, that’s it. If Google Duo is not showing Contacts on your device, then make sure to follow these troubleshooting methods and try to fix it up. Let me know in the comments section if you have got any queries relating to this guide.
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