@r15niloy Are you using any case or screen protector? If so, please remove it and see if your issue persists.
You can also try the following:
Make sure you are using the latest available firmware (2107.151) for your device.
Clear cache files system-wide (Settings -> Advanced -> Mobile manager -> Cleanup)
Clear the storage of Armoury Crate (bear in mind this will reset all of your AC settings).
Reboot your device.
If none of the above resolves your issue, please consider performing a factory reset. (Mare sure you backup any personal data before as this will wipe your device.)
If the ultrasonic buttons are still acting up I'll send you instructions on how to log your device so we can take a closer look at what's happening.