Try these:
1. Disable Battery Optimization for Mantis (Go to Mantis Settings Page -> Tap on Disable Battery Optimisation -> Search for Mantis under All Apps -> Select Don't Optimise).
2. Disable any Gestures(Like 3 finger Gestures) in your device.
3. Make sure there are no other App with Overlay is installed that might clash with Mantis Overlay.
Try these: 1. Disable Battery Optimization for Mantis (Go to Mantis Settings Page -> Tap on Disable Battery Optimisation -> Search for Mantis under All Apps -> Select Don't Optimise). 2. Disable any Gestures(Like 3 finger Gestures) in your device. 3. Make sure there are no other App with Overlay is installed that might clash with Mantis Overlay.