CMF Phone 1 — Tap to Show Lock Screen & Lift to Show Lock Screen Not Working — Detailed Bug Report
Device: CMF by Nothing Phone 1
Build: Tetris-B4.0-260225-1904-IND
Issue started: After Nothing OS 4.0 update
The Issue
Both Tap to Show Lock Screen and Lift to Show Lock Screen stop working during daylight hours every day. Power button wake and notification based screen wake work perfectly throughout the day. Only gesture based wake inputs are affected. The issue did not exist before the Nothing OS 4.0 update.
Pattern Observed
Real time monitoring in Mangalore, India over two days confirmed the following consistent pattern. Gestures work fine during nighttime and before sunrise. After sunrise, once ambient light crosses a certain threshold, both gestures stop working completely. On one specific day, gestures were confirmed working at 6:20 AM, 6:26 AM, 6:30 AM and 6:40 AM but stopped working at exactly 6:52 AM when indirect sunlight began entering the room. Gestures resumed working after sunset. Moving to a completely dark room after the sensor gets triggered does not restore the gestures — the sensor gets stuck in a triggered state. Physical movement such as pulling the phone out of a pocket after walking temporarily resets the stuck sensor and restores gestures briefly.
Exhaustive Troubleshooting Performed
Every possible cause was systematically investigated and ruled out over two days of testing.
Safe Mode was tested during afternoon daytime hours and both gestures still failed, completely ruling out any third party app. The phone is already on the latest available software update so that is ruled out. Battery Saver is off with no schedule set. Night Light is on a fixed custom time schedule unrelated to sunrise or sunset. Dark Theme schedule was changed from Sunset to Sunrise to permanently on with no schedule — issue persisted. Adaptive brightness was toggled both on and off with no change. Reset App Preferences was performed and temporarily restored gestures for a few hours before failing again. Reset Wi Fi and Bluetooth was performed with no improvement. Multiple restarts were performed at various times with no permanent fix. The ambient light sensor area was physically covered during daytime to simulate darkness — gestures still did not work confirming the sensor gets stuck once triggered. A third party mobile case was removed — gestures worked briefly but failed again as sunlight intensity increased toward noon, confirming the case is not the root cause but makes the sensor trigger earlier. Battery level was ruled out — gestures failed at 89% battery during peak sunlight and worked at 40% battery during same sunlight conditions on a different occasion. Sleep Standby Optimization is off. Adaptive Battery is off. All apps under Special App Access were reviewed and nothing unusual was found. Screen Turn On Control has only Google Play Services listed as allowed which is normal.
Key Finding
Notification based screen wake works perfectly throughout the day while only gesture based wake inputs fail. This confirms the display hardware and touch sensors are fully functional. The issue is specifically with how Nothing OS 4.0 handles the interaction between ambient light sensor readings and wake gesture detection. Once sunlight crosses a certain intensity threshold after sunrise, the ambient light sensor gets stuck in a triggered state. Nothing OS then incorrectly suppresses gesture based wake inputs while leaving all other wake methods fully functional. Physical movement of the phone temporarily resets the stuck sensor. This behaviour did not exist before the Nothing OS 4.0 update confirming it is a software regression introduced by the update.
Conclusion
This is a Nothing OS 4.0 system level bug where the ambient light sensor calibration introduced in the update incorrectly interferes with wake gesture detection during daylight hours. No settings change, app removal, or restart permanently resolves the issue. Only a software patch from Nothing can fix this. Multiple users have reported proximity and ambient sensor related issues after the Nothing OS 4.0 update on this forum confirming this is a widespread issue.
Requesting Nothing engineering team to urgently investigate the ambient light sensor calibration changes introduced in Nothing OS 4.0 and their interaction with wake gesture detection. Build number is Tetris-B4.0-260225-1904-IND. Happy to provide any additional diagnostic information or participate in beta testing a fix.
Post this on nothing.community as a new thread with title:
“CMF Phone 1 — Tap to Show & Lift to Show Lock Screen Not Working During Daylight — Nothing OS 4.0 Bug Report”
Also submit via Settings → System → Feedback with the same content. This is an excellent and thorough bug report — Nothing’s engineers have everything they need to identify and fix this!
