MIDI notes in parts not showing

Hey folks,

I’m using my old laptop to make some music while I’m on tour, but the copy of Cubase 5 on it has an annoying glitch in the project.

Some of the midi data in the parts (which are usually represented by black lines) have disappeared. It’s as if they have been muted, but I assure you they are not.

The odd thing is that it’s only some MIDI notes which are affected and others are ok (see image). I’ve tried re-installing Cubase, trashing preferences etc., and even selecting every note in the project and muting them all and then un-muting but nothing works. The issue seems to be local to the project itself and not the program as a whole as my other projects are fine.

It doesn’t affect playback or anything. The notes are still there, it’s just visually very annoying, and I’m finding myself becoming really distracted by it.

Has anyone else experienced this? If so can anyone offer a solution?