Holy shit. It’s working!!! 
Mark, you my friend are a genius!
Adding those tiny lines of code seems to have solved everything.
But only as long as I never enter the midi settings and select the 2hp module as my midi device.
Because if I do so aconnect -x, aconnect 128:1 28:0 magically disappears from patch_loaded.sh.
Although I’m sure it’s not really magic.
Is there anyway around this?
Cool - glad it’s working for you.
Ok, my guess here is that for some reason attaching the 2hp midi as an input , is somehow causing issues with using it as an output.
Unfortunately, midi settings menu rewrites this file.
So just avoid doing this for now.
The best approach, for a future OS update, to solve this is to allow for a separate input and output device - as this is a pretty common use case anyway.