Why-Garnet-gets-surprised-by-steven's-fusions theory

"Garnet's future vision should have told her that fusion could happen"

Yes, it did, but it only showed a probability, she knows as much of Steven as the other CGs do, so she couldn't have 100% know that he could fuse

She keeps that probability as the last of the opcions therefore she can only see the result come true (of her future vision) once its already present

I dont know how to explain myself any further in english, but would like to hear your thoughts