Scaler Audio Unit (AU) does not provide input for external VST in Ableton Live

Versions:
Scaler 2.7.2
Ableton Live 11.2.7
macOS Monterey on M2

Unlike VST3, the AU version of Scaler does not provide an input as shown in this screenshot. Which makes the AU unable to send notes to another track, and prevents this routing Use Case.

This is a limitation of the AU spec and not Scaler. Scaler cannot add what is not in the plug-in specifications. Until Apple changes that you need to use the VST or VST3 version. This works perfectly in Ableton Live.
Cheers and welcome to the forum.

ah ok, so no workarounds either. I was attempting to see if VST issue by using AU because I ran into this issue Scaler bug - always plays pattern even without MIDI when Ableton Live playing

Got my other issue fixed and will continue to use the VST3, thanks!