I repeat, if Performer can hear playback but not your TB, you will not see the VST Connect plugins’ Cue Meter move when you spek into your mic, right?
Which means the TB path is not complete: input port not set correctly, TB in Control Room not set and/or TB in VST Connect Cue plugin not activated.
And as dr already pointed out: “its the same project… so i don’t think there could be any errors in routing…” - not true, as CR settings are local to each Cubase/Nuendo version.
This might also help: https://helpcenter.steinberg.de/hc/en-us/articles/360012899079