Logic Pro External Midi channel strips disappeared from mixer

[rainerschnelle]

All of a sudden the channel strips of my external Midi instruments have disappeared from the mixer. I can see the recorded tracks in the arrange area but the corresponding channel strips in the mixer are gone. This has happened to the most recent two songs I was working on. In older songs everything appears normal.

 

[EdgarRothermich]

In the Mixer Window, in the upper right corner is a MIDI Button. This toggles the view of the External MIDI Tracks in the Mixer.
Maybe you disabled it by accident.