9 month old talking

So my 9 month old started saying simple words like mama and yay at 8 months old. now I can’t get her to say them. Is this normal? I’m a little concerned. She used to repeat them back to me or she would come to me saying mama. Now she won’t say any of them at all.

She still babbles and makes noises she just doesn’t say actual words anymore. And yes she has been learning new things like how to shake her head yes and no and how to wave.