If you're talking about day 33 that's just making sure the NTR route bar is bigger than the NTS route bar - I don't think that'll work in the day replayer you'll probably need to go back to an older save and play through the full NTR route?
So the flag that triggers that scene is set on day 30 on MC's POV when NTR > NTS and the actual scene happens on day 30 on Vanilla's POV (after finishing day 30 MC POV)
The day 29 group chat doesn't have the scene it's actually on the day 30 group chat so maybe that's where the confusion is