Ah damn ... sorry, somehow I missed that 2nd post of yours.
And no, inserting a monitor object in the VSL 1x16 ports AU2 template made no difference that I can see.
I need to know what versions of Logic, VEPro, macOS and Mac computer you're using in your testing.
In my test on your AU2 monitor object idea I used Logic 10.7.2 and VEPro 7.0.1056 (local host) in macOS 11.6.3. I'm running a 2017 iMac 27", 4.2GHz i7 7700K, 64GB DDR4, Radeon Pro 580 8GB.
I have previously tried the Beta VEPro 7.0.1151 (several days before you mentioned your Monitor idea) but it made no difference so I uninstalled it and went back to 1056.
In the test I've just done on your idea I played back a few notes created by the MIDI region editor. I haven't run my usual full suite of tests for MIDI response. Finding that playing back editor-created notes is still problematic was all I needed to know in this particular case.
I'm not stuck. I have a fully operational AU3 template using Logic 10.4.8 and VEpro 7.0.1056 in High Sierra. For my normal everyday work I'm not looking to change this configuration in the forseeable future; however, for special purposes I can dual-boot between High Sierra and Big Sur.