The Performer Track Monitor button should not be engaged at all. You can hear the Performer at any time thru the VST Connect Monitor plugin in the Control Room Main Output (set up automagically when you “Create VST Connect”).
I’m confused, as the track monitor button has absolutely nothing to do what the Performer hears, only with what you hear (and you get a delay when you engage it on a Performer track so that’s why you shouldn’t).
Your Talkback mic signal is entering the Control Room and from there goes to the Performer via the VST Connect Cue. So when you talk in the Studio, you should see the “CUE” meters on top of the VST Connect plugin interface move. If they don’t, Performer can not hear you. Then either Talkback is disabled or you haven’t assigned the mic (menu Devices/VST Connections/Studio/Talkback). Also note that TB is usually automatically disabled during playback/record so not to confuse the Performer (delay).
If it all fails pls. try to describe exactly what you do and what you expect. Also an “Empty” project and then “Create VST Connect” should always work.