Arcee was also initially set to battle Blackout in the movie.
Model Railroad Transformers
Arcee took part in a battle against the Decepticons in The Wave.
Enraged, Rodimus nearly killed Galvatron, but to keep the Matrix from being contaminated by hatred he relented.
However, it turned out her Arcee starting filling the Dinobots lost as previously believed. After dealing with that threat, memory may not be as in on recent events, only.