The Aerophone AE-20/AE-20W preset Brasswinds scenes have "Fall" or "Harmony" assigned to the [S2] button. If the sound cuts off unexpectedly, an unintended key may be pressed during playing.
For preset scene "06: Brasswinds - 01 Trumpet," the Down Fall effect is applied when blowing into the instrument while pressing [S2]. The Down Fall effect stops the sound after the last note is played, which may appear as though no sound is being produced. If this occurs with certain fingering, check that no unintended keys are being pressed. See also the related Q&A, "Even though my fingering is correct, the pitches are not changing correctly."