Scroll down your events list and see if there are changes in instrument patches, I have seen this in midi I have had problems before. I have erased the instrument patches from the beginning to end before and chose the sounds I wanted manually and it cleared up problems. Also events that have only 0 as a value can sometimes be a problem , especially if it appears to be of an unknown use. Most have at least 1 as a value . Save it as a new name in case it won't work after the changes.