There is also a filter that can be set to choose what types of MIDI-events that should be displayed in the microscope. Check the menu "View" in micro-mode.

The most likely reason for this, is that the data is recorded to the wrong track. It can still be recorded with the right channel, so that it plays with the correct sound. This is a mistake that is sometimes hard to detect. I've done it myself a couple of times.. :-)

Stig