If the [MOD/FX] knob is set to "SYNTH" and you play chords, the sound may cut out or the pitch may be off due to the pitch analysis not handling multiple notes at once.
To avoid this, play single notes and mute other strings. If switching between notes, mute the previous note completely and ensure a clear attack on the next note.
The sensitivity can also vary based on the TONE knob and the type of pickups on your guitar or bass.