Eat my flower trail achievement not unlocked

[Biita]

I beat both ida and hayate three times, getting both the gimmick gear and the stray bead, and the game didn't give me the achievement. what gives?

[Dadang Sudadang]

The achievement system tends to be wonky and often not registered properly unfortunately. If you have any save prior to beating them the third time, maybe try reloading the save and beat them again.