I loaded a midi instrument and was able to play it with my MPK Mini keyboard through MIDI. I deleted the instrument from the track list using Shift-T and also from the instrument list by right clicking and choosing Remove. It does not show in the channel list. The instrument still plays but I cannot see it in any instrument list to disconnect it from the MIDI channel or remove it. If I add a new instrument, the removed instrument still sounds. If I add the removed instrument back in, it simply acts as a new instance and the old, "removed" version is still active. How can I remove the "removed" instrument?