If your phone is having an issue related to contact, we suggest checking the items below
Contact list opens more slowly than usual
1. Change to a different SIM card.
2. Too many phone numbers in the phone book may result in slow reading.
3. Check if it installs any third-party phone app, it is recommended to uninstall third-party apps.
4. Open Setting - Apps & notifications - Calls - Storage - CLEAR CACHE. (For Android O: Open Setting - Apps - Calls - CLEAR CACHE)
5. If the issue still persists, please back up all the data, clear cache and flash to the latest OS version.
Can't edit contacts
1. Check if any third-party phone app is installed, it is recommended to uninstall third-party apps and try again.
2. Check whether the edited contact is on the SIM card. If yes, we recommend changing the SIM card to test. This could be due to an error on the SIM card.