Hello  @Lynn1989 

Thank you for the feedback, if you can not view playback

1. Force close the Tapo APP on your first phone (in case the app is still running on the background)

2. Reboot Tapo camera . In Camera Live view> tap the ' Wheel' icon on the right top and go to Camera Settings> reboot camera

Or Factory reset the camera and reinstall the camera in the app. 

3. Make sure the device camera and Tapo APP are both up to date

4. Make sure SD card status is good, and you can view SD card contents  on the computer first. 

If still the same, may I know the model of your phone and its OS version, and Tapo APP version?

Please help collect the log of camera How to Get the Log of Tapo Camera 

Please share the MAC address of camera with us via PM, thank you.