She had plenty of flirtatious scenes with Ivy in the same series she was introduced in. But, as you said, she also flirts with Batman a few times too in that same series. It was less a "clearly she is into this person seriously" and more of a "there is still a girl under the costume craving affection/kindness."

The problem with her is that they never actually ironed out her character, so it has never been actually solidified to prevent her from being changed so much. So a couple of flirty fanservice scenes with Ivy during a random teamup becomes "full lesbian."

They still haven't decided if she slept with her professors to get through school, was a hard working if dumb girl doing her best to escape being white trash, or an actually smart person who did it on her own and the Joker took advantage of to ruin. All of which massively change everything about where you can take her from there.