3D Touch is Apple’s exclusive technology launched with iPhone 6 which allows quick actions for most iOS apps and tasks. Users can access the 3D touch features by pressing the screen little more pressure than other device. However with same iPhone backup 3D touch is working fine with older iPhone 7.
However some iPhone X users are facing the issue that the 3D touch not working on iPhone X/8. The issue seems to annoying as this is Apple latest iPhone released by Apple is not working fine with old features. The user have tried resetting device, hard reboot and complete restore to fix the issue but none of them seems to help to fix the 3D touch issue.
Why 3D touch is nor working properly with iPhone X:
Many people are claiming this to be software glitch but the issue is not reported across different models of iPhone. Also the users have tried to upgrade to latest iOs 11.2 but still facing the issue. So quite possible that this can be hardware of faulty screen issue. As apple has first time came up with OLED screens on iPhone X so that could be also one of the reasons.
So far there are no updates from Apple on the issue and many Apple genuine bars are not able to provide any good explanation or fix for 3D touch issue. There are some workaround for the Touch issue that you may try:
Fix 1: Change 3D touch sensitivity
As 3D touch in iPhone offer users reasonschoice for making pressure on the screen for invoking 3D touch specific behaviour, you may try to alter the sensivity in 3D touch setting and see if that help.
Fix 2: Remove any screen protector
In case you have put on some screen protector on iPhone X, try to remove it and test 3D touch without screen protector. It is possible that screen guard are causing 3D touch fail.
Fix 3: Get your iPhone X screen replaced to fix the issue:
If you can manage to get an Apple support appointment and they are not able to fix the issue ask to get your OLED screen replace as this is probably most likely reason for 3D touch not working in iPhonX