Input level loss in External Midi strip

Hello!! I recently experienced a 20db input level drop in all the External Midi channel strips of a concert.

It's alway the same instrument, just different strips in different patches. It's a B3 clone that I process in MainStage for a better Leslie sound.

To be clear, it's not Aliases. I created one new strip in every song that needed the B3. To permit different settings in different songs.

Always the same hardware inputs and same hardware outputs for the audio part.

Suddenly, all of these EXT Midi strips lost 20db. The B3 went down 20db in all the songs. Between 2 sets of the same gig on the same day...

Strangely, if I create a new EXT Midi strip with the same I/O, I get the gain back to normal.

If I reset the faulty strip and then Undo the reset operation, I get the strip back WITHOUT the I/O assignments. If I reselect the right I/O, the level comes back ok.

That's what I did for all the faulty EXT Midi strips throughout the whole concert.

Anybody have an idea on what caused this?

First time I encounter that bug in 15 years. And don't want it to happen again.

Thanks community!!