Wont stay asleep in crib

I can lay my 4 month old down drowsy and she will fall asleep in her crib.. but will not stay asleep, she wakes up after 20 mins like clock work flailing her arms and crying (I know it’s a confinement thing, she’s used to her rock n play where she would sleep like a rock all night)

The 20 mins must be one sleep cycle

But I get her up and rock her back to drowsy and try again.

We did this 5 times last night before I gave up.

I am completely against cry it out... so I guess any other tips ?

Is is just about repetition until she finally feels more comfortable in there?