Sounds as though the MIDI drum kit has lost one or more settings:

Try the following and check that the definition values are not zero. If so, change them to match the following values and save:

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BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones