Scaler2 MIDI IN for external instruments tracks (in Live 11) are missing, for Scaler 2.8.x AU on Intel MacOS 11.6.8

for Scaler 2.6.x VST i have no issue routing to external instrument tracks.
However, realizing i should be running the AU plugin on my intel Mac, I was surprise that a Scaler 2.8.x once inserted into a track, the assocated external instrument tracks NO LONGER can route from Scaler in both of the MIDI In fields, only the upper field. in the lower MIDI IN field,the pulldown menu only lists prefx and postfx,and “Scaler 2” is GONE so you cant get those tracks to input scaler’s MIDI
I have screenshots but hopefully the description above suffices.

and the reason for doing so would be no doubt much lower CPU cycles load for AU than for VST Scaler2 plugin (right?) I’m having some CPU load issues so I suspected the VST scaler… but i can’t wire up the AU to replace it

This is a limitation in the AU spec. It doesn’t allow for this. Until Apple corrects or adds it then Scaler can’t use it correctly. This is no fault of Scaler.