Falls Asleep Sitting Up.. What to do?

Crystal • Mother of an amazing daughter (Jan. '16)... and an amazing son (Oct. '17). Two under 2 💗
We've recently transition from baby sleeping with us to her sleeping in her crib. 
I put her in her crib, drowsy, laying down. As i walk out, she freaks out, and sits up and cries. 
She cries for about 10 min and starts dosing off. We have a video monitor and i watch her wobble back and forth as she is sitting up falling asleep. 
I don't know what to do. Every time i go in to lay her back down, the whole process starts over. 
Should i just leave her and know eventually she will lay down? I mean, if i just had a sound monitor, i guess i would never know she was sitting up falling asleep. But i just feel so bad. It can't be comfortable for her. :-/