Motivation->Recruit->Flirt.
Did you get the post Farrow Facility e-mail thanking you? (Actually receiving/reading the e-mail isn't necessary, but it does tell you if you set the Flag correctly.)
Post your save for inspection? There was someone earlier who had a save without the Danced flag set correctly. It's possible there was a bug in some version that got fixed eventually, if you did the party a long time ago.
"SHINEGLASS_RIVAL_MOTIVATION":1What are the flags for having flirted on the train?