I have some updates… both original non-nav APIM connector and the new nav APIM connector have pins in 12+13, not 5+6.
I popped in my original non-nav APIM and lo and behold… voice commands + mic does NOT work either (even after a master reset)! I think the last time it worked was on 3.0.x prior to my 3.4 upgrade.
So that leaves two Sync 3 APIMs on 3.4.23188 without a working microphone. It appears to be a software issue at this point so hopefully someone has a suggestion on that end.
@F150Chief suggested a few years ago to downgrade (Sync 3.4 Microphone Fix - #2 by F150Chief)
Is 3.4 19101 still recommended or should I try something else?