You are shielded from ooze.

<x> 

You feel yourself slowly rising from the quicksand.
You struggle to escape the quicksand, but the weight of your belongings drags you back in!
....

Healer closes her eyes for a moment and nods at you.
Your feet rise off the ground.

<x> 

You feel yourself slowly rising from the quicksand.
You struggle to escape the quicksand, but the weight of your belongings drags you back in!

>Oozeshield fell before I walked into the room. I fell in the
>sand then I casted oozeshield. I got stuck in the sand and
>couldn't get out. Even when the healer casted flight on me I
>couldn't get out.

By design. Being oozeshielded or flying after you fall in the quicksand greatly improves your chances to get out, but doesn't make it 100%.

So long, and thanks for all the fish!